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Li P.,CAS Shenyang Institute of Metal Research | Li P.,Ruhr University Bochum | Li S.X.,CAS Shenyang Institute of Metal Research | Wang Z.G.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2017

By analyzing the formation mechanisms of different types of dislocation patterns, one unified factor is developed to account for effects of slip mode and further explore the basic law of dislocation evolution in fatigued face-centered cubic (fcc) crystals. First of all, in the formation of persistent slip band (PSB) ladders, geometrically necessary dislocations (GNDs) accommodate the elastic/plastic strain gradients between the hard walls and soft channels and provide the long-range internal stresses required for the simultaneous compatible deformation of soft and hard regions. In typical wavy-slip materials, advanced dislocation patterns include the wall, cell and labyrinth structures. The formation of deformation band (DB) walls may be derived from the accumulation of GNDs. The appearance of labyrinth and cell structures should be related to the activation of critical and coplanar secondary slip systems, respectively. In typical planar-slip materials, the dislocation structures consist of the dipole arrays and stacking fault (SF) bands. The constant compression of the split distance between partials will lead to the conversion of the closely spaced dipole array to the SF bands, which indicates that both wavy-slip and planar-slip materials follow one unified evolution factor. This factor, labelled α in this work, may be described as the ratio of the annihilation distance of screw dislocations to the split distance between partials, which can characterize the slip mode. The higher the α value is, the easier will be the appearance of PSBs and various advanced dislocation patterns. With decreasing the α value, dislocation evolution gradually changes from 3D patterns to 2D structures. © 2017 Acta Materialia Inc.


Lu L.,Tongji University | Ni S.,China Academy of Engineering Physics | Liu G.,CAS Shenyang Institute of Metal Research | Xu X.,Tongji University
International Journal of Hydrogen Energy | Year: 2017

The crystal structure of a photocatalyst generally plays a pivotal role in its electronic structure and catalytic properties. In this work, we synthesized a series of La/Cr co-doped perovskite compounds ATiO3 (M = Ca, Sr and Ba) via a hydrothermal method. Their optical properties and photocatalytic activities were systematically explored from the viewpoint of their dependence on structural variations, i.e. impact of bond length and bond angles. Our results show that although La/Cr co-doping helps to improve the visible light absorption and photocatalytic activity of these wide band gap semiconductors, their light absorbance and catalytic performance are strongly governed by the TiO bond length and TiOTi bond angle. A long TiO bond and deviation of TiOTi bond angle away from 180° deteriorate the visible light absorption and photocatalytic activity. The best photocatalytic activity belongs to Sr0.9La0.1Ti0.9Cr0.1O3 with an average hydrogen production rate ∼2.88 μmol/h under visible light illumination (λ ≥ 400 nm), corresponding to apparent quantum efficiency ∼ 0.07%. This study highlights an effective way in tailoring the light absorption and photocatalytic properties of perovskite compounds by modifying cations in the A site. © 2017 Hydrogen Energy Publications LLC.


Wu L.,CAS Shenyang Institute of Metal Research | Yang Z.,Northeastern University China | Qin G.,Northeastern University China
Journal of Alloys and Compounds | Year: 2017

A novel electroless nickel-phosphorus (Ni[sbnd]P) process employing tetrasodium pyrophosphate and ammonium citrate as complexing agents and nickel hypophosphite as the nickel source which avoids the use of SO4 2− and Cl− ions was developed to improve the anti-corrosion properties of AZ91D magnesium alloy. The dependence of the electroless deposition rate on experimental parameters, the morphologies of the electroless deposit and the corrosion resistance of the electroless deposit were studied by the weight-gain method, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS), respectively. An empirical equation was formulated to predict the Ni[sbnd]P deposition rate. The results showed that tetrasodium pyrophosphate played a major role in the deposition process, followed by ammonium citrate, nickel hypophosphite, sodium hypophosphite and pH. The Ni[sbnd]P coating significantly enhances the corrosion resistance of AZ91D Mg alloy. © 2016 Elsevier B.V.


Li Y.,CAS Shenyang Institute of Metal Research | Xu J.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2017

In this work, commercially pure niobium (c.p. Nb) was selected to study its electrochemical behaviour in artificial saliva with several concentrations of fluoride ions (F−) over a range of 0–0.24 M. The chemical nature of passive layers on surface was characterised with x-ray photoelectron spectroscopy (XPS). The changes in surface topography due to F−-induced corrosion were examined with scanning electron microscopy (SEM). For comparison, commercially pure titanium (c.p. Ti) was also investigated under identical conditions. Both c.p. Nb and c.p. Ti exhibit very good corrosion resistance in artificial saliva without F− or with a low level of F−, showing a low passive current density (jpass) and high polarisation resistance (Rp). However, as the F− concentration increases, c.p. Nb demonstrates a significantly greater corrosion resistance due to its stable passive film (mainly Nb2O5) with a thickness of several nanometres, showing a much lower jpass and higher Rp, with both values differing from those of c.p. Ti by over one order of magnitude. Significant differences in the corrosion behaviour between c.p. Nb and c.p. Ti can be understood from the thermodynamic perspective and the propensity of oxide dissolution. The advantage of niobium over titanium merits attention, as the c.p. Nb and Nb-based alloys are promising for further applications in dental prosthesis fabrication. © 2017 Elsevier Ltd


Xiong L.,CAS Shenyang Institute of Metal Research | You Z.S.,CAS Shenyang Institute of Metal Research | You Z.S.,Nanjing University of Science and Technology | Lu L.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2017

A bulk nanotwinned austenitic stainless steel containing a large volume fraction of deformation twins was produced by dynamic plastic deformation. The tensile tests and J-integral fracture toughness measurements indicate that this steel exhibits a combination of high strength (σys = 920 MPa) and considerable fracture toughness (KJC > 126 MPa m1/2). The fracture is associated with localized shear band induced destruction of the nanotwinned structure and with micro-void development at the generated nanoscale large angle grain boundaries within the shear bands, which consumes large plastic energy and contributes the fracture resistance. © 2016 Acta Materialia Inc.


Kim B.,University of Vienna | Liu P.,University of Vienna | Liu P.,CAS Shenyang Institute of Metal Research | Franchini C.,University of Vienna
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

Using ab initio methods, we investigate the modification of the magnetic properties of the m=2 member of the strontium iridates Ruddlesden-Popper series Srm+1IrmO3m+1, bilayer Sr3Ir2O7, induced by epitaxial strain and oxygen vacancies. Unlike the single-layer compound Sr2IrO4, which exhibits a robust in-plane magnetic order, the energy difference between in-plane and out-of-plane magnetic orderings in Sr3Ir2O7 is much smaller and it is expected that small external perturbations could induce magnetic transitions. Our results indicate that epitaxial strain yields a spin-flop transition, which is driven by the crossover between the intralayer J1 and interlayer J2 magnetic exchange interactions upon compressive strain. While J1 is essentially insensitive to strain effects, the strength of J2 changes by one order of magnitude for tensile strains ≥3%. In addition, our study clarifies that the unusual in-plane magnetic response observed in Sr3Ir2O7 upon the application of an external magnetic field originates from the canting of the local magnetic moments due to oxygen vacancies, which locally destroy the octahedral networks, thereby allowing for noncollinear spin configurations. © 2017 American Physical Society.


Liu Z.,CAS Shenyang Institute of Automation | Ma T.,CAS Shenyang Institute of Metal Research | Liu L.,CAS Shenyang Institute of Automation
Tribology International | Year: 2017

Recently, large-area high-quality single-crystal graphene domains have been be fabricated using modified chemical vapor deposition (CVD). These hexagonal graphene domains have edges of zigzag chirality and micrometer size, which makes it possible to study the friction anisotropy properties caused by lattice orientations with multi-scale method. In this paper, an optical-assistant characterization method is first put forward. With the micro-scale optical system, the spatial relationship between the hexagonal graphene domain and the probe of the atomic force microscopy (AFM) was determined and changed gradually. Then a series of atomic-scale friction experiments were conducted under ambient conditions utilizing AFM lateral mode. During the process, the probe scanned along various lattice orientations with sample rotation method, which gets ride of the probe's anisotropic effect caused by the cantilever and the tip. And the stick-slip behaviors of the probe during this process were observed and recorded precisely. The scanning experimental results unveiled that the patterns of the stick-slip behaviors varied along different lattice orientation, which is caused by the distribution of graphene surface potential. The comparison between theoretical and experimental results shows that these variations can be regarded as the origin of the friction anisotropy on the graphene domains. The achievements will not only provide an effective method for the identification of lattice orientation, but also lay a more solid experimental base for multiscale research on graphene. The presented work can also provide a standard process for studies on various properties of graphene depended on lattice distribution. © 2017 Elsevier Ltd


Bai F.X.,CAS Shenyang Institute of Metal Research | Yao J.H.,CAS Shenyang Institute of Metal Research | Wang Y.X.,CAS Shenyang Institute of Metal Research | Pan J.,CAS Shenyang Institute of Metal Research | Li Y.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2017

The crystallization behavior of Au50Cu25.5Ag7.5Si17 metallic glass during continuous heating/cooling and isothermal treatment is investigated by ultrafast calorimetry. The relationship between the transformation and the time/temperature scales of the alloy is established experimentally in a wide temperature range from glass transition temperature to the melting point. Temperature-dependent viscosity in the expanded supercooled liquid region is derived from the thermodynamic and kinetic analysis of the crystallization behavior of the metallic glass. The nucleation rate and growth velocity for crystallization of the supercooled liquid are analyzed by applying classical nucleation theory and diffusion-controlled growth theory. © 2017 Acta Materialia Inc.


Luo S.S.,CAS Shenyang Institute of Metal Research | You Z.S.,CAS Shenyang Institute of Metal Research | You Z.S.,Nanjing University of Science and Technology | Lu L.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2017

A contactless video crack opening displacement gauging system based on digital image correlation technique was established to measure the load-line displacement of miniaturized fracture toughness samples precisely. The intrinsic fracture toughness and smoothly rising R-curve of bulk dynamic plastic deformation (DPD) Cu with nanotwin bundles embedded in nano-grained matrix were measured through elastic-plastic unloading compliance method using miniaturized side-grooved compact tension specimens. Nanotwin bundles exert positive bearings on enhancing the damage tolerance of the DPD Cu. © 2017 Acta Materialia Inc.


Sun Z.,CAS Shenyang Institute of Metal Research | Zhang J.,CAS Shenyang Institute of Metal Research | Yin L.,CAS Shenyang Institute of Metal Research | Hu G.,CAS Shenyang Institute of Metal Research | And 4 more authors.
Nature Communications | Year: 2017

Although the rechargeable lithium-sulfur battery is an advanced energy storage system, its practical implementation has been impeded by many issues, in particular the shuttle effect causing rapid capacity fade and low Coulombic efficiency. Herein, we report a conductive porous vanadium nitride nanoribbon/graphene composite accommodating the catholyte as the cathode of a lithium-sulfur battery. The vanadium nitride/graphene composite provides strong anchoring for polysulfides and fast polysulfide conversion. The anchoring effect of vanadium nitride is confirmed by experimental and theoretical results. Owing to the high conductivity of vanadium nitride, the composite cathode exhibits lower polarization and faster redox reaction kinetics than a reduced graphene oxide cathode, showing good rate and cycling performances. The initial capacity reaches 1,471 mAh g-1 and the capacity after 100 cycles is 1,252 mAh g-1 at 0.2 C, a loss of only 15%, offering a potential for use in high energy lithium-sulfur batteries. © The Author(s) 2017.


Wang X.D.,CAS Shenyang Institute of Metal Research | Qu R.T.,CAS Shenyang Institute of Metal Research | Liu Z.Q.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2017

Shear bands play dominant roles in fatigue damage and fracture of metallic glasses (MGs). In order to explore the effect of cyclic loading on the shear banding behavior, interrupted cyclic compression-compression experiments combined with scanning electron microscope observations using a typical Zr-based MG were performed. With increasing the number of loading cycles, shear bands firstly progressively propagate and eventually stop growing. In contrast to the apparent “work-hardening” behavior caused by the progressive propagation of shear band under monotonic loading, plastic softening occurs and then reaches saturation under cyclic compression. Such cyclic softening behavior is suggested to result from the production of excessive free volume in MGs, which decreases the critical stress for shear band initiation. These findings may improve the understanding on fatigue damage mechanisms and provide instructions for future design of MGs with excellent fatigue performance. © 2016 Elsevier B.V.


Wang Z.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Beilstein Journal of Nanotechnology | Year: 2017

Gradient nanostructures (GNSs) have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed. © 2017 Wang and Lu.


Wan P.,CAS Shenyang Institute of Metal Research | Wan P.,University of Chinese Academy of Sciences | Gao L.,CAS Shenyang Institute of Metal Research | Gao L.,University of Chinese Academy of Sciences | Wang J.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2017

The crucial challenge for oxide thermal insulators, such as Al2O3 and SiO2 nano-particle aggregates, is to solve the trade-off between extremely low thermal conductivity and unsatisfied sintering stability. We herein report the ultra-low thermal conductivities (0.068–0.1 W m− 1 K− 1) of β-SiC nanoparticle (~ 35 nm) packed beds. The breakthrough is realized by multiple heat blocking mechanisms in the nanostructures. The samples also possess good thermal stability as high as 1500 °C. Our results provide a new strategy to explore ultra-low thermal conductivity materials with excellent thermal stability, regardless of their high intrinsic lattice thermal conductivities. © 2016 Acta Materialia Inc.


Song Z.-Q.,CAS Shenyang Institute of Metal Research | Ma E.,Johns Hopkins University | Xu J.,CAS Shenyang Institute of Metal Research
Intermetallics | Year: 2017

The torsional properties of the Zr61Ti2Cu25Al12 BMG have been tested using cylinder samples, including the shear yield strength, shear elastic strain limit and shear modulus. Under torsional loading, the BMG fails via a major shear band, without obvious macroscopic plasticity on the specimen surface. The shear band maintained stable propagation by a distance of ∼300 μm (∼20% of cylinder radius) before final catastrophic failure, owing to the constraint of stress gradient along the radial direction. The combined tensile, compressive and torsional properties of the Zr61Ti2Cu25Al12 BMG suggest that recent ellipse criterion and eccentric ellipse criterion are more appropriate than other well-known ones in describing the yield behavior of this BMG. The cooperative shear model underestimates the shear elastic strain limit, because of its default assumption that the yielding behavior follows the Tresca yield criterion. © 2017 Elsevier Ltd


Bai F.X.,CAS Shenyang Institute of Metal Research | Bai F.X.,University of Chinese Academy of Sciences | Yao J.H.,CAS Shenyang Institute of Metal Research | Li Y.,CAS Shenyang Institute of Metal Research
Intermetallics | Year: 2017

In the present work, the compatibility of additivity rule with the crystallization behavior of an Au50Cu25.5Ag7.5Si17 glass forming alloy on the conditions of both isothermal and isochronal transformations is investigated. Taking advantages of the ultrafast heating and cooling rates of the Flash DSC technique, we verified the additivity rule in a solidification process for the first time. It is proved to be effective in predicting the beginning and the end of isochronal crystallizations during continuous heating and cooling from the kinetic analysis of corresponding experimental isothermal transformation. The predicted isochronal curves are fairly in accordance with the experimental results, especially for the incubation and crystallization processes during rapid solidification of the glass forming liquid. The compatibility of additivity rule enables a conversion between isothermal and isochronal transformations for the crystallization of supercooled liquid even during solidification from the melt. © 2017 Elsevier Ltd


Zhu Q.,CAS Shenyang Institute of Metal Research | Zhu Q.,University of Chinese Academy of Sciences | Wang S.-Q.,CAS Shenyang Institute of Metal Research
Applied Surface Science | Year: 2017

Bimetallic surface alloys have been considered as an effective strategy to achieve better catalytic performance and to modify the work function of the substrate toward metal-gate electrode application. We perform a systematical investigation of Group 10 and Group 11 transition metals adsorption on Rh (111), Ru (0001) and W (110) surfaces with various coverages using first-principles method. Through comparing the Bader charge results and the plots of work function shift, it is found that the polarization effect plays an important role in modification of the bimetallic surface work functions rather than the charge transfer effect especially at low coverages. The coverage-dependent work function behavior gives a general feature: as it has a large negative shift at 0.25ML coverage, then increases almost linearly with the coverage and followed by a saturation value which is controlled by the lattice strain. It is also found that the metal over-layer growth modes are correlated with the specific features of the coverage-dependent metal-substrate adhesion energy. All these findings may give some guidelines for the bimetallic catalysts design in terms of growth, stability and activity. © 2017 Elsevier B.V.


Liang F.,CAS Shenyang Institute of Metal Research | Liang F.,University of Science and Technology of China | Tan H.-F.,Northeastern University China | Zhang B.,Northeastern University China | Zhang G.-P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2017

The tensile fracture behavior of the sandwich-structured Ni/Cu/Ni composites was investigated. The results reveal that an evident transition of the fracture behavior from the necking-delayed ductile mode with sufficient co-deformation of both-side Ni layers to the necking-inhibited brittle mode accompanied by interface delamination with decreasing the thickness ratio of the middle Cu layer to the Ni layer. A model based on beam deflection was proposed to elucidate the role of the Ni layers in delaying necking of the Cu layer. © 2017 Acta Materialia Inc.


Sun Q.,CAS Shenyang Institute of Metal Research | Sun Q.,University of Science and Technology of China | Jiang H.,CAS Shenyang Institute of Metal Research | Zhao J.,CAS Shenyang Institute of Metal Research | He J.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2017

Solidification experiments were carried out for Al-Bi alloys with the addition of TiC. It is demonstrated that the average size of the Bi-rich minority phase particles (MPPs) shows a tendency of keeping constant, increasing, decreasing and then keeping constant again with the increase of the additive amount of TiC. The MPPs can be refined effectively with the addition of an appropriate amount of TiC. A model was developed to describe the kinetic behavior of the TiC particles in the melt and the microstructure evolution during the liquid-liquid (L-L) phase transformation of the Al-Bi alloys with the addition of TiC. The numerical results show that TiC particles may dissolve and coarsen during the heating period, and precipitate out during the cooling period of the melt. There may be two kinds of TiC particles: the one remained during holding temperature and the one precipitated during a cooling of the melt. Both of them can work as the inoculants for the nucleation of the minority phase droplets. What determines the refining efficiency is the resultant number density of the TiC particles in the melt cooled to the binodal line temperature. This research demonstrates that inoculation is an effective method for controlling the L-L phase transformation. The addition of the efficient inoculant may promote the formation of a monotectic alloy with a well dispersed microstructure. © 2017


Yao B.,CAS Shenyang Institute of Metal Research | Han Z.,CAS Shenyang Institute of Metal Research
Tribology International | Year: 2017

Bulk nanostructured Cu sample with nano-scale twin bundles embedded in nano-sized grains was synthesized by using dynamic plastic deformation (DPD) technique. Dry sliding tribological properties of the DPD and the coarse grained (CG) Cu samples were investigated when sliding against different counterfaces. There is an obvious difference in the relative wear resistance of the DPD to the CG Cu as a result of the change of the counterface materials. Either for the DPD Cu or the CG Cu sample, the wear rate was much larger when sliding against Cu ball than that when sliding against WC-Co or AISI 52100 steel ball. The DPD Cu sample shows almost same wear rate compared with the CG Cu sliding against Cu or AISI 52100 steel ball, which is quite different from the enhanced wear resistance for the DPD Cu sample sliding against WC-Co ball. The worn subsurface structure for two kinds of Cu samples sliding against different counterfaces, was constituted by heavily deformed nanostructured mixing layer (NML) and ultra-fine grained dynamic recrystallization (DRX) layer. Structure characteristics of the NML and DRX layer determines wear rates of the Cu samples. When sliding against Cu or AISI 52100 steel ball, there are heavily cracked NMLs and extremely fine DRX grains in the subsurface, comparing with that sliding against WC-Co ball. This structure feature leads to quick spread of cracking and high flaking rate of the NML, which corresponds to much higher wear rate for both Cu samples. © 2017 Elsevier Ltd.


Jia H.,CAS Shenyang Institute of Metal Research | Feng X.,CAS Shenyang Institute of Metal Research | Yang Y.,CAS Shenyang Institute of Metal Research | Yang Y.,Shandong Key Laboratory for High Strength Lightweight Metallic Materials
Corrosion Science | Year: 2017

The microstructure and corrosion resistance of directionally solidified Mg-2. wt.% Zn alloy with different growth rates were investigated. Optical microscopy observations showed that the microstructure of directionally solidified Mg-2Zn alloy transformed from coarse cellular to fine cellular, undeveloped dendritic and finally dendritic structures as the growth rate increased from 20. μm/s to 60. μm/s, 120. μm/s and 200. μm/s, respectively. The results of electrochemical measurement and immersion test in 0.9. wt.% NaCl solution revealed that the corrosion resistance of directionally solidified Mg-2Zn alloy strongly depends on the microstructure. The samples with fine cellular structure have the highest corrosion resistance, which mainly due to the reduction of susceptible grain boundaries and homogenous distribution of Zn element. © 2017 Elsevier Ltd.


Han Y.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research | Peng Q.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2017

Effects of changes in surface chemical composition and microstructure by electropolishing on corrosion and stress corrosion cracking (SCC) of Alloy 182 in high temperature water were investigated. The results showed that electropolishing mitigated the corrosion, intergranular corrosion and SCC of Alloy 182. This is attributed to formation of the Cr-enriched, protective oxide on electropolished surface due to the enrichment of Cr by electropolishing. In particular, formation of the protective, blunted oxide at grain boundaries on electropolished surface mitigated the intergranular corrosion and caused a lower SCC susceptibility of Alloy 182. © 2017 Elsevier Ltd.


Gao X.,Northwestern Polytechnical University | Zeng W.,Northwestern Polytechnical University | Zhang S.,Northwestern Polytechnical University | Wang Q.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2017

The epitaxial growth behaviors of equiaxed primary α phase (αp) at different cooling rates (150–0.15 °C/s) in a near α titanium alloy Ti60 were studied by optical micrograph, back scattered electron (BSE) images, high-resolution electron backscatter diffraction technique (EBSD) and electron probe microanalysis (EPMA). Microstructural observations indicated that the size of αp significantly increased with decreasing cooling rate. The rim-α phase observed by BSE image, which formed at the periphery of αp during cooling and has an identical crystallographic orientation to the interior region of αp analyzed by Kikuchi diffraction patterns, is considered to be evidence of epitaxial growth of αp. EBSD analysis also showed that αp preferentially grew extending for a distance along the β/β boundary resulting in extension-α phase from αp. The EPMA confirmed that contrast difference in BSE image within αp is caused by the difference in composition. The further microanalysis of local composition indicated that epitaxial growth during continuous cooling is mainly controlled by the diffusional redistribution of aluminum and molybdenum atoms between αp and β matrix. On this basis, the sizes of αp were theoretically calculated after continuous cooling based on a diffusion-controlled model, and model predictions showed good agreement with experimental measurements. © 2016 Acta Materialia Inc.


Sheng L.Y.,China Institute of Technology | Du B.N.,China Institute of Technology | Guo J.T.,CAS Shenyang Institute of Metal Research
IOP Conference Series: Materials Science and Engineering | Year: 2017

NiAl based materials has been considered as most potential candidate of turbine blade, due to its excellent high-temperature properties. However the bad room-temperature properties handicap its application. In the present paper, the zirconium doped NiAl/Cr(Mo) hypoeutectic alloy is fabricated by conventional casting and injection casting technology to improve its room-temperature properties. The microstructure and compressive properties at different temperatures of the conventionally-cast and injection-cast were investigated. The results exhibit that the conventionally-cast alloy comprises coarse primary NiAl phase and eutectic cell, which is dotted with irregular Ni2AlZr Heusler phase. Compared with the conventionally-cast alloy, the injection-cast alloy possesses refined the primary NiAl, eutectic cell and eutectic lamella. In addition, the Ni2AlZr Heusler phase become smaller and distribute uniformly. Moreover, the injection casting decrease the area fraction of primary NiAl phase at the cell interior or cell boundaries. The compressive ductility and yield strength of the injection-cast alloy at room temperature increase by about 100% and 35% over those of conventionally-cast alloy, which should be ascribed to the microstructure optimization. © Published under licence by IOP Publishing Ltd.


Lu L.,Tongji University | Lv M.,Tongji University | Wang D.,Tongji University | Liu G.,CAS Shenyang Institute of Metal Research | Xu X.,Tongji University
Applied Catalysis B: Environmental | Year: 2017

Graphical abstract: Fe plays a critical role in constituting spin-polarized bands inside the intrinsic band gap of SrTiO3, therefore is responsible for band gap reduction and visible light activities of Sr1-xBiTi1-xFeO solid solutions. Constituting solid solutions for prototype perovskite compound SrTiO3 offers appealing means to tailor the optical and photocatalytic properties of this wide band gap semiconductor. Here we successfully synthesized a series of Sr1-xBiTi1-xFeO (0≤x≤0.5) solid solutions via hydrothermal method. Their crystal structures, surface nature and other physicochemical properties were systematically explored. Our results show that a large portion of BiFeO3 (up to 50%) can be incorporated into the structure SrTiO3 without symmetry degradation from cubic. A number of important factors such as microstructures, light absorbance and surface hydrophilicity are all strongly correlated with Bi/Fe content in the solid solutions. Photocatalytic performance was greatly improved after formation of solid solutions and high activity normally occurs in samples with large surface area, high crystallinity as well as absence of Bi (V) species. The highest activity belongs to sample Sr0.6Bi0.4Ti0.6Fe0.4 with photocatalytic hydrogen production rate ∼50μmol/h under full range irradiation and ∼5μmol/h under visible light irradiation, corresponding to apparent quantum efficiency ∼0.63% and 0.11%, respectively. Theoretical calculation reveals the critical role of Fe in constituting spin-polarized bands inside the intrinsic band gap of SrTiO3, therefore is responsible for band gap reduction and visible light activities. This work highlights the benefits of forming solid solutions in the design and development of efficient photocatalysts. © 2016 Elsevier B.V.


Lu L.,Tongji University | Lv M.,Tongji University | Wang D.,Tongji University | Liu G.,CAS Shenyang Institute of Metal Research | Xu X.,Tongji University
Applied Catalysis B: Environmental | Year: 2017

Constituting solid solutions for prototype perovskite compound SrTiO3 offers appealing means to tailor the optical and photocatalytic properties of this wide band gap semiconductor. Here we successfully synthesized a series of Sr1-xBixTi1-xFexO3 (0 ≤ x ≤ 0.5) solid solutions via hydrothermal method. Their crystal structures, surface nature and other physicochemical properties were systematically explored. Our results show that a large portion of BiFeO3 (up to 50%) can be incorporated into the structure SrTiO3 without symmetry degradation from cubic. A number of important factors such as microstructures, light absorbance and surface hydrophilicity are all strongly correlated with Bi/Fe content in the solid solutions. Photocatalytic performance was greatly improved after formation of solid solutions and high activity normally occurs in samples with large surface area, high crystallinity as well as absence of Bi (V) species. The highest activity belongs to sample Sr0.6Bi0.4Ti0.6Fe0.4O3 with photocatalytic hydrogen production rate ∼50 μmol/h under full range irradiation and ∼5 μmol/h under visible light irradiation, corresponding to apparent quantum efficiency ∼0.63% and 0.11%, respectively. Theoretical calculation reveals the critical role of Fe in constituting spin-polarized bands inside the intrinsic band gap of SrTiO3, therefore is responsible for band gap reduction and visible light activities. This work highlights the benefits of forming solid solutions in the design and development of efficient photocatalysts. © 2016 Elsevier B.V.


Hu J.,CAS Shenyang Institute of Metal Research | Shi Y.N.,CAS Shenyang Institute of Metal Research | Sauvage X.,INSA Rouen | Sha G.,Nanjing University of Science and Technology | And 2 more authors.
Science | Year: 2017

Conventional metals become harder with decreasing grain sizes, following the classical Hall-Petch relationship. However, this relationship fails and softening occurs at some grain sizes in the nanometer regime for some alloys. In this study, we discovered that plastic deformation mechanism of extremely fine nanograined metals and their hardness are adjustable through tailoring grain boundary (GB) stability. The electrodeposited nanograined nickel-molybdenum (Ni-Mo) samples become softened for grain sizes below 10 nanometers because of GB-mediated processes. With GB stabilization through relaxation and Mo segregation, ultrahigh hardness is achieved in the nanograined samples with a plastic deformation mechanism dominated by generation of extended partial dislocations. Grain boundary stability provides an alternative dimension, in addition to grain size, for producing novel nanograined metals with extraordinary properties.


Wei X.,CAS Shenyang Institute of Metal Research | Peng X.,CAS Shenyang Institute of Metal Research | Wang X.,CAS Shenyang Institute of Metal Research | Dong Z.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2017

The development of growth and thermal stresses in the NiO scale on a nanocrystalline (NC) Ni without and with the dispersion of CeO2 nanoparticles during isothermal oxidation in air at 800°C and subsequent cooling has been analyzed by using a two-sided oxidation deflection testing. The CeO2 dispersion causes the NC Ni to form a NiO scale which accommodates higher growth stresses during oxidation but lower thermal stresses during cooling. The result is interpreted by characterization of the effect of CeO2 dispersion on the growth mechanism and microstructure of the NiO scale on the NC Ni. © 2017 Elsevier Ltd.


Song K.,CAS Shenyang Institute of Metal Research | Du K.,CAS Shenyang Institute of Metal Research | Ye H.,CAS Shenyang Institute of Metal Research
Micron | Year: 2017

Oxide thin films with perovskite structures possess multifunctional properties, while defects in the films usually have significant influences on their physical properties. Here, the atomic structure and chemistry of a[100] dislocation cores in epitaxial La2/3Sr1/3MnO3 films were investigated by aberration-corrected scanning transmission electron microscopy combining with atomically resolved electron energy-loss spectroscopy imaging. The results demonstrated an edge dislocation terminated with Mn columns and significant nonstoichiometry at the dislocation core region. Quantitative analysis using core-loss spectrum indicates that La/Mn and O/Mn ratios are decreased at the dislocation core. Antisite defects with Mn ions at La-sites were directly determined at the dislocation cores with electron energy-loss spectroscopy. The structure of the dislocation core is discussed on the basis of high-angle annular dark-field imaging and electron energy loss spectroscopy results. © 2017 Elsevier Ltd


Wang Z.T.,National University of Singapore | Pan J.,National University of Singapore | Li Y.,National University of Singapore | Li Y.,CAS Shenyang Institute of Metal Research | Schuh C.A.,Massachusetts Institute of Technology
Physical Review Letters | Year: 2013

The deformation of metallic glasses involves two competing processes: a disordering process involving dilatation, free volume accumulation, and softening, and a relaxation process involving diffusional ordering and densification. For metallic glasses at room temperature and under uniaxial loading, disordering usually dominates, and the glass can fail catastrophically as the softening process runs away in a localized mode. Here we demonstrate conditions where the opposite, unexpected, situation occurs: the densifying process dominates, resulting in stable plastic deformation and work hardening at room temperature. We report densification and hardening during deformation in a Zr-based glass under multiaxial loading, in a notched tensile geometry. The effect is driven by stress-enhanced diffusional relaxation, and is attended by a reduction in exothermic heat and hardening signatures similar to those observed in the classical thermal relaxation of glasses. The result is significant, stable, plastic, extensional flow in metallic glasses, which suggest a possibility of designing tough glasses based on their flow properties. © 2013 American Physical Society.


Kim C.W.,Sogang University | Yeob S.J.,Sogang University | Cheng H.-M.,CAS Shenyang Institute of Metal Research | Kang Y.S.,Sogang University
Energy and Environmental Science | Year: 2015

In the present study, a selectively exposed (101)-crystal facet engineered TiO2 photoanode is investigated for the higher efficiency of the hydrogen evolution reaction. To date, even though the photoelectrochemical performance (PEC) dependent on exposed crystal facets has been calculated and demonstrated in semiconducting microcrystals, selectively exposed crystal facets of photocatalyst thin films have not been reported yet. Herein, we demonstrate a TiO2 thin film photoanode with 100%-exclusively exposed crystal facets and suggest a methodology to obtain metal oxide thin film photoanodes with selectively exposed crystal facets. A selectively exposed crystal facet-manipulated metal oxide thin film photoanode is fabricated over pre-synthesized microcrystals through a three-step strategy: (1) hydrothermal synthesis of microcrystals, (2) positioning of microcrystals via polymer-induced manual assembly, and (3) fabrication of selectively exposed crystal facets of a TiO2 thin film through a secondary growth hydrothermal reaction. Based on the synthesis of representative TiO2 microcrystals with dominantly exposed (101), (100) and (001) crystal facets, the selectively exposed crystal faceted TiO2 thin film photoanode is comparatively investigated for practical PEC performance. The photocurrent density of the selectively exposed (101) crystal faceted TiO2 thin film photoanode is determined as 0.13 mA cm-2 and has an 18% conversion efficiency of incident photon-to-current at a 0.65 V Ag/AgCl potential under AM 1.5G illumination. Its photoelectrochemical hydrogen production reached 0.07 mmol cm-2 for 12 h, which is higher than those of (100) and (001) faceted photoelectrodes. © 2015 The Royal Society of Chemistry.


Feng Q.,Nanjing University | Feng Q.,Fujian Normal University | Tang N.,Nanjing University | Liu F.,Nanjing University | And 5 more authors.
ACS Nano | Year: 2013

Fluorination was confirmed to be the most effective route to introduce localized spins in graphene. However, adatoms clustering in perfect graphene lead to a low efficiency. In this study, we report experimental evidence of the generation of localized spin magnetic moments on defective graphene (reduced graphene oxide) through fluorination. More interstingly, the result shows that defects help increase the efficiency of the fluorination with regard to the density of magnetic moments created. Fluorinated reduced graphene oxide can have a high magnetic moment of 3.187 × 10-3 μB per carbon atom and a high efficiency of 8.68 × 10-3 μB per F atom. It may be attributed to the many vacancies, which hinder the clustering of F atoms, and introduce many magnetic edge adatoms. © 2013 American Chemical Society.


Xu C.,CAS Shenyang Institute of Metal Research | Wang L.,Peking University | Liu Z.,CAS Shenyang Institute of Metal Research | Chen L.,CAS Shenyang Institute of Metal Research | And 5 more authors.
Nature Materials | Year: 2015

Transition metal carbides (TMCs) are a large family of materials with many intriguing properties and applications, and high-quality 2D TMCs are essential for investigating new physics and properties in the 2D limit. However, the 2D TMCs obtained so far are chemically functionalized, defective nanosheets having maximum lateral dimensions of ∼10μm. Here we report the fabrication of large-area high-quality 2D ultrathin α-Mo2C crystals by chemical vapour deposition (CVD). The crystals are a few nanometres thick, over 100 μm in size, and very stable under ambient conditions. They show 2D characteristics of superconducting transitions that are consistent with Berezinskii-Kosterlitz-Thouless behaviour and show strong anisotropy with magnetic field orientation; moreover, the superconductivity is also strongly dependent on the crystal thickness. Our versatile CVD process allows the fabrication of other high-quality 2D TMC crystals, such as ultrathin WC and TaC crystals, which further expand the large family of 2D materials. © 2015 Macmillan Publishers Limited.


Zhang M.-X.,University of Queensland | Huang H.,University of Queensland | Shi Y.-N.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2010

Cold spraying of pure Al powder on a pure Mg substrate together with subsequent post-spray annealing treatment produced Mg17Al12 (β-phase) and Mg2Al3 (γ-phase) intermetallic layers on the surface of the substrate. These layers showed significantly better nanomechanical properties, including the reduced elastic modulus and nanohardness, which were determined using nanoindentation, than commercial purity Mg and AZ91 alloys. Combined with their improved corrosion resistance, it is believed that both the γ-phase and the β-phase layers can provide effective protection of Mg alloys from wear and corrosion. The effect of post-spray annealing process on the formation of thick, uniform and dense intermetallic layers on pure Mg substrate was also investigated. © 2009 Elsevier B.V. All rights reserved.


Zhang T.,Xi'an University of Science and Technology | Zhao H.,Xi'an University of Science and Technology | He S.,Xi'an University of Science and Technology | Liu K.,Xi'an University of Science and Technology | And 3 more authors.
ACS Nano | Year: 2014

Ultrasmall gold nanoparticles (us-AuNPs, <3 nm) have been recently recognized as surprisingly active and extraordinarily effective green catalysts. Their stability against sintering during reactions, however, remains a serious issue for practical applications. Encapsulating such small nanoparticles in a layer of porous silica can dramatically enhance the stability, but it has been extremely difficult to achieve using conventional sol-gel coating methods due to the weak metal/oxide affinity. In this work, we address this challenge by developing an effective protocol for the synthesis of us-AuNP@SiO2 single-core/shell nanospheres. More specifically, we take an alternative route by starting with ultrasmall gold hydroxide nanoparticles, which have excellent affinity to silica, then carrying out controllable silica coating in reverse micelles, and finally converting gold hydroxide particles into well-protected us-AuNPs. With a single-core/shell configuration that prevents sintering of nearby us-AuNPs and amino group modification of the Au/SiO2 interface that provides additional coordinating interactions, the resulting us-AuNP@SiO2 nanospheres are highly stable at high temperatures and show high activity in catalytic CO oxidation reactions. A dramatic and continuous increase in the catalytic activity has been observed when the size of the us-AuNPs decreases from 2.3 to 1.5 nm, which reflects the intrinsic size effect of the Au nanoparticles on an inert support. The synthesis scheme described in this work is believed to be extendable to many other ultrasmall metal@oxide nanostructures for much broader catalytic applications. © 2014 American Chemical Society.


Zhang Y.,CAS Shenyang Institute of Metal Research | Liu B.,Shanghai University | Wang J.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2016

The carbon deficiency and the ordering of carbon vacancies (VCs) in ZrC1-x are well known phenomena and significant for the performance management and service reliability. Using first-principles calculations to identify structural characteristics and stabilities, we report three kinds of vacancy-ordered phases, stable, metastable and "faulted" structures among vast ZrC1-x configurations. The intrinsic elasticity and hardness of ordered ZrC1-x are shown in linear dependence on carbon composition. In contrast, the thermal conductivity of ZrC1-x is not only dependent on the composition, but also strongly modified by the vacancy configuration. These results ensure the prediction of mechanical properties and also provide a guideline to tailor the thermal conductivity of ZrC1-x through tuning the VC characteristics. The variable-composition, diverse-configuration and tunable-property of ZrC1-x promise the engineering of its ordered phases, service performance and consequently the extension of its technological applications in the future. © 2016 Acta Materialia Inc.


Zhang J.,CAS Shenyang Institute of Metal Research | Liu Y.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Zhang X.,Sichuan Agricultural University | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2013

Fusarium graminearum is the pathogen for Fusarium head blight (FHB) on wheat, which could significantly reduce grain quality/yield and produce a variety of mycotoxins posing a potential safety concern to human foods. As an environmentally friendly alternative to the commonly used chemical fugicides, a highly effective photocatalytic disinfection of F. graminearum macroconidia under visible light illumination was demonstrated on a visible-light-activated palladium-modified nitrogen-doped titanium oxide (TiON/PdO) nanoparticle photocatalyst. Because of the opposite surface charges of the TiON/PdO nanoparticles and the F. graminearum macroconidium, the nanoparticles were strongly adsorbed onto the macroconidium surface, which is beneficial to the photocatalytic disinfection of these macroconidia. The photocatalytic disinfection mechanism of TiON/PdO nanoparticles on these macroconidia could be attributed to their cell wall/membrane damage caused by the attack from reactive oxygen species (ROSs) as demonstrated by the fluorescence/phase contrast microscopy observations, while a breakage of their cell structure was not necessary for their loss of viability. © 2013 American Chemical Society.


Nan L.,CAS Shenyang Institute of Metal Research | Yang K.,CAS Shenyang Institute of Metal Research | Ren G.,University of Hertfordshire
Materials Science and Engineering C | Year: 2015

Abstract Staphylococcus aureus (S. aureus) is a bacterium frequently found proliferating on metal surfaces such as stainless steels used in healthcare and food processing facilities. Past research has shown that a novel Cu-bearing 304 type stainless steel (304CuSS) exhibits excellent antibacterial ability (i.e. against S. aureus) in a short time period (24 h.). This work was dedicated to investigate the 304CuSS's inhibition ability towards the S. aureus biofilm formation for an extended period of 7 days after incubation. It was found that the antibacterial rate of the 304CuSS against sessile bacterial cells reached over 99.9% in comparison with the 304SS. The thickness and sizes of the biofilms on the 304SS surfaces increased markedly with period of contact, and thus expected higher risk of bio-contamination, indicated by the changes of surface free energy between biofilm and the steel surfaces. The results demonstrated that the 304CuSS exhibited strong inhibition on the growth and adherence of the biofilms. The surface free energy of the 304CuSS after contact with sessile bacterial cells was much lower than that of the 304SS towards the same culture times. The continuously dissolved Cu2+ ions well demonstrated the dissolution ability of Cu-rich precipitates after exposure to S. aureus solution, from 3.1 ppm (2 days) to 4.5 ppm (7 days). For this to occur, a hypothesis mechanism might be established for 304CuSS in which the Cu2+ ions were released from Cu-rich phases that bond with extracellular polymeric substances (EPS) of the microorganisms. And these inhibited the activities of cell protein/enzymes and effectively prevented planktonic bacterial cells attaching to the 304CuSS metal surface. © 2015 The Authors.


Qu R.T.,CAS Shenyang Institute of Metal Research | Liu Z.Q.,CAS Shenyang Institute of Metal Research | Wang G.,Shanghai University | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2015

Shear band plays a key role in dominating the strength and plasticity of metallic glasses, and exhibits two kinds of propagation modes under compression, i.e., progressive and simultaneous propagation. These two different propagation modes of shear bands lie in different stages of plastic deformation. Prior to macroscopic yielding, shear bands have already been initiated yet not penetrated through the sample. These inserting shear bands exhibit linearly decreasing plastic strain from the end to tip, demonstrating a progressive propagation mode. Once the macroscopic yielding occurs, the major shear band fully transects the sample and propagates in a simultaneous sliding manner. The progressive propagation of shear bands causes an apparent work-hardening behavior, which can be well explained by assuming a higher critical stress for shear band initiation than propagation. The results demonstrate that metallic glasses with a smaller difference between critical conditions for initiation and propagation of shear band should have better plastic deformability, which can be reflected by the plastic strain to macroscopic yielding read from stress-strain curves. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wang J.,CAS Shenyang Institute of Metal Research | Zhou L.,CAS Shenyang Institute of Metal Research | Sheng L.,Peking University | Sheng L.,ShenZhen HongKong Institution | Guo J.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2012

The microstructure evolution and its influence on the mechanical properties are investigated in a hot-corrosion resistant Ni-based superalloy during long-term thermal exposure. It is found that the tertiary γ' phase disappears and the secondary γ' phase coarsens and coalesces gradually, which acts as the main reason for the decreasing of strength at both room temperature and 900°C. During exposure, the grain boundary coarsens from discontinuous to half-continuous and finally to continuous structure. The optimum half-continuous grain boundary structure composed of discrete M23C6 and M3B2 wrapped by γ' film leads to the elongation peak at room temperature in the thermally exposed specimens. At 900°C, the increase in the elongation is attributed to the much softer matrix and the formation of microvoids. The behavior of primary MC decomposition is a diffusion-controlled process. During exposure, various derivative phases including M23C6, γ', η, M6C and σ sequentially form in the decomposed region. Primary MC decomposition and the precipitation of σ phase have little effect on the mechanical properties due to their low volume fractions. © 2012 Elsevier Ltd.


Sheng L.Y.,PKU HKUST ShenZhen Hong Kong Institution | Sheng L.Y.,Peking University | Yang F.,Shenzhen Airlines | Xi T.F.,Peking University | And 2 more authors.
Intermetallics | Year: 2012

The NiAl-Cr(Nb)/Dy alloy was fabricated by conventionally casting and rapid solidification and treated by hot isostatic pressing treatment (HIP). The results reveal that Cr 2Nb phase contains much of Ni and Al elements and retains the C14 crystal structure at room temperature. The rapid solidification refines the NiAl phase, Cr 2Nb phase and needle-like Cr 2Nb precipitates in NiAl matrix. Moreover the rapid solidification increases α-Cr phase and results in the formation of Cr 7Ni 3 phase with stacking faults and microtwins inside. The HIP treatment transforms the needle-like Cr 2Nb precipitate in the NiAl phase into sphere shape and blunts the tip of the Cr 2Nb phases along the NiAl phase boundary. In addition, the HIP treatment leads to some moveable dislocations in the alloy, which is beneficial to the compressive ductility. The mechanical test shows the rapidly solidified alloy with HIP treatment has the best mechanical properties, whose compressive ductility is more than ten times that of the as cast alloy. © 2012 Elsevier Ltd. All rights reserved.


Wang B.,Zhejiang Normal University | Yang Y.-S.,CAS Shenyang Institute of Metal Research | Sun M.-L.,Zhejiang Normal University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2010

The effects of a pulsed magnetic field on the solidified microstructure of an AZ31 magnesium alloy were investigated. The experimental results show that the remarkable microstructural refinement is achieved when the pulsed magnetic field is applied to the solidification of the AZ31 alloy. The average grain size of the as-cast microstructure of the AZ31 alloy is refined to 107 μm. By quenching the AZ31 alloy, the different primary α-Mg microstructures are preserved during the course of solidification. The microstructure evolution reveals that the primary α-Mg generates and grows in globular shape with pulsed magnetic field, contrast with the dendritic shape without pulsed magnetic field. The pulsed magnetic field causes melt convection during solidification, which makes the temperature of the whole melt homogenized, and produces an undercooling zone in front of the liquid/solid interface, which makes the nucleation rate increased and big dendrites prohibited. In addition, the Joule heat effect induced in the melt also strengthens the grain refinement effect and spheroidization of dendrite arms. © 2010 The Nonferrous Metals Society of China.


Sheng L.-Y.,Peking University | Yang F.,Shenzhen Airline | Xi T.-F.,Peking University | Zheng Y.-F.,Peking University | Guo J.-T.,CAS Shenyang Institute of Metal Research
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2013

The NiAl-Cr(Mo)-(Hf,Dy) hypoeutectic alloys were prepared by conventional casting and injection casting techniques respectively, and their microstructure and room temperature mechanical properties were investigated. The results reveal that with the addition of Hf and Dy, the Ni2AlHf Heusler phase and Ni5Dy phase form along the NiAl/Cr(Mo) phase boundaries in intercellular region. By the injection casting method, some Ni2AlHf Heusler phase and Ni5Dy phase transform into Hf and Dy solid solutions, respectively. Moreover, the microstructure of the alloy gets good optimization, which can be characterized by the fine interlamellar spacing, high proportion of eutectic cell area and homogeneously distributed fine Ni 2AlHf, Ni5Dy, Hf solid solution and Dy solid solutions. Compared with conventional-cast alloy, the room temperature mechanical properties of injection-cast alloy are improved obviously. © 2013 The Nonferrous Metals Society of China.


Zeng R.-C.,Shandong University of Science and Technology | Zeng R.-C.,CAS Shenyang Institute of Metal Research | Sun L.,Shandong University of Science and Technology | Zheng Y.-F.,Peking University | And 2 more authors.
Corrosion Science | Year: 2014

The influence of the microstructure and the oxide film of the Mg-9.29Li-0.88Ca alloy on its corrosion behaviour was investigated using SEM, EPMA, XPS and corrosion measurements. The results demonstrated that the fine-grained microstructure improved the mechanical and corrosion resistance of the alloy and shifted pitting corrosion to overall corrosion. The oxide film contained a multi-layered structure, with the outer layer being enriched in lithium-bearing compounds; the interior layer predominantly consisting of oxides, hydroxides and carbonates of lithium and magnesium; and the bottom layer containing oxides. The Pilling-Bedworth ratio for chemical compounds was proposed, and the corrosion rates were characterised. © 2013 Elsevier Ltd.


Li L.-X.,University Of Science And Technology Liaoning | Li F.,CAS Shenyang Institute of Metal Research
Xinxing Tan Cailiao/New Carbon Materials | Year: 2011

Concentrated H2SO4:HNO3 mixed acids, air, nitric acid and potassium permanganate were used to oxidize carbon nanotubes (CNTs) to introduce surface functional groups (SFGs) and the effects of the type and amount of SFGs on the electrochemical properties of CNT supercapacitors were investigated. XPS analysis shows that the mixed acid oxidation produces carbonyl (C=O) and the carboxyl (C-O=O) groups, the air oxidation results in hydroxyl and the smallest amount of carbonyl and carboxyl groups, and both the nitric acid and potassium permanganate treatments result in a moderate amount of carbonyl and carboxyl groups. It was found that the specific surface area and pore structures of the four samples are similar and carbonyl and carboxyl groups contribute the most to pseudo-capacitance through a Faradic reaction. In particular, the carbonyl group has a proportional relationship to the capacitance of CNTs. However, the hydroxyl group does not lead to an obvious increase of pseudo-capacitance, but can increase the electric double layer capacitance. The carbonyl and the carboxyl groups are advantageous for fast Faradic reactions to introduce pseudo-capacitance, owing to their lower charge transfer resistance than that of the hydroxyl group.


Wang J.,CAS Shenyang Institute of Metal Research | Wang J.,University Of Science And Technology Liaoning | Wang J.,Hefei University of Technology | Wang S.-Q.,CAS Shenyang Institute of Metal Research
Surface Science | Year: 2014

The surface energies and work functions for six close-packed surfaces of 19 common fcc and bcc metals in the periodic table have been systematically calculated by means of the density functional theory (DFT) method. The accuracy of the results is established in comparison with the experimental and other theoretical values. The variations of work functions with the surface crystallographic orientation display a good regularity. For alkali metals, the work functions follow the sequence Φ(110) > Φ(133) > Φ(311) > Φ(120) > Φ(100) > Φ(111). But for the same crystal structure of bcc transition metals (Nb, Mo, Ta, W), the order is Φ(110) > Φ(133) > Φ(120) > Φ(111) > Φ(311) > Φ(100). The work functions for 3d, 4d and 5d transition fcc metals also display an obvious regularity and ordered as Φ(111) > Φ(100) > Φ(211) > Φ(123) > Φ(310) > Φ(110). Particular attention is paid to the surface energies anisotropy with the same crystal structure metals and the variations present a good regularity, too. Especially, a roughly inverse proportional relationship between the surface energy and work function is found. © 2014 Elsevier B.V. All rights reserved.


Hu Y.,Peking University | Liang Z.,CAS Shenyang Institute of Metal Research
Physical Review Letters | Year: 2011

In quasi-two dimensions (quasi-2D), where excitations are frozen in one direction, the scattering amplitudes exhibit 2D features of the particle motion and a 3D to 2D dimensional crossover emerges in the behavior of scattering. We explore its physical consequences, capitalizing on a hidden connection between the Pitaevskii-Rosch dynamical symmetry and breathing modes. We find broken Pitaevskii-Rosch symmetry by arbitrarily small 2D effects, inducing a frequency shift in breathing modes. The predicted shift rises significantly from the order of 0.5% to more than 5% in transiting from the 3D-scattering to the 2D-scattering regime. Comparisons with other relevant effects suggest our results are observable within current experimental capabilities. © 2011 American Physical Society.


Sheng L.Y.,PKU HKUST ShenZhen HongKong Institution | Sheng L.Y.,Peking University | Yang F.,Shenzhen Airlines | Guo J.T.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Composites Part B: Engineering | Year: 2013

The NiAl-TiC-Al2O3 in situ composite was fabricated by self-propagation high temperature synthesis and hot extrusion (SHS/HE) technique using element powders. Its microstructure and mechanical properties were investigated by OM, SEM, TEM and compression test. The results revealed that the NiAl-TiC-Al2O3 composite was densified by the SHS/HE process and had fine microstructure. In the composite, TiC particles along NiAl grain boundary agglomerated and grew, but the TiC particles in NiAl grain were fine. The TiC and Al2O3 particles exhibited an obvious trend to distribute along extrusion direction. Moreover, stacking fault and microtwins in TiC particles and thin amorphous layer along NiAl/TiC phase interface were also observed. In addition, Ti2AlC particle with intergrowth TiC plate inside formed along the NiAl grain boundary. Generally the SHS/HE synthesized NiAl-TiC-Al2O3 composite possessed better mechanical properties, especially at room temperature, which should be ascribed to the fine microstructure and predeformation caused by hot extrusion. © 2012 Elsevier Ltd. All rights reserved.


Sheng L.Y.,Peking University | Yang F.,Shenzhen Airlines | Xi T.F.,Peking University | Guo J.T.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2013

NiAl-TiC-Al2O3 composite was fabricated by self-propagation high-temperature synthesis with extrusion technique. Its microstructure, compressive properties and wear behavior at 873, 973, 1073 and 1173 K were investigated. The results reveal that the NiAl-TiC-Al 2O3 composite exhibits self-lubricating behavior and excellent wear resistance properties at 973 K, which should be ascribed to the lubricant film formed on the surfaces of the NiAl-TiC-Al2O 3 composite and SiC friction pair during the sliding wear test. TEM observation shows that the lubricant film is composed of amorphous and NiO and Al2O3 nanoparticles, while the matrix adjacent to the lubricant film mainly contains NiAl and Ni3Al nanocrystalline. While at 873, 1073 and 1173 K, lubricant film on the composite surface is spalled partly or greatly, which results in the increase of the friction coefficient and the wear rate. In summary, the NiAl-TiC-Al2O3 composite could form the lubricant film at high temperature and possess good wear resistance. © 2012 Elsevier B.V. All rights reserved.


Bianco A.,CNRS Strasbourg Institute of Chemistry | Cheng H.-M.,CAS Shenyang Institute of Metal Research | Enoki T.,Tokyo Institute of Technology | Gogotsi Y.,Drexel University | And 7 more authors.
Carbon | Year: 2013

Interest in two-dimensional, sheet-like or flake-like carbon forms has expanded beyond monolayer graphene to include related materials with significant variations in layer number, lateral dimension, rotational faulting, and chemical modification. Describing this family of "graphene materials" has been causing confusion in the Carbon journal and in the scientific literature as a whole. The international editorial team for Carbon believes that the time has come for a discussion on a rational naming system for two-dimensional carbon forms. We propose here a first nomenclature for two-dimensional carbons that could guide authors toward a more precise description of their subject materials, and could allow the field to move forward with a higher degree of common understanding.


Sheng L.,Peking University | Sheng L.,PKU HKUST ShenZhen Hong Kong Institution | Wang L.,University of Science and Technology Beijing | Xi T.,Peking University | And 2 more authors.
Materials and Design | Year: 2011

The microstructure and mechanical properties of NiAl-28Cr-6Mo-0.2Hf eutectic alloys with various holmium additions have been investigated by using of SEM, TEM and compression test. The results reveal that minor Ho addition could optimize the microstructure by refining the lamella inside of eutectic cell and controlling the coarsening of intercellular region. However the minor Ho addition results in the Ni2Al3Ho phase, which has hexagonal crystal structure and an orientation relationship with NiAl phase of [120]Ni2Al3Ho//[111]NiAl and (002̄)Ni2Al3Ho//(11̄0)NiAl. Moreover the Ni17Ho2 phase is found in the Ni2Al3Ho phase, which has twin crystal inside and an orientation relationship with Ni2Al3Ho phase of [123]Al17Ho2//[124]Ni2Al3Ho and (111̄)Al17Ho2//(2̄10)Ni2Al3Ho. In addition, the Ho addition promotes the precipitation of Ni2AlHf phase. More Ho addition coarsens the Cr(Mo) phases along the intercellular and results in more strengthening precipitates inside eutectic cell. When the Ho addition comes to 0.5at.%, the alloy almost loses the cellular eutectic characteristic and exhibits a microstructure with coarse NiAl, massive Cr(Mo) and Ni2Al3Ho phases. The microstructure optimizations improve the mechanical properties of the alloy significantly, especially the alloy with 0.1at.% Ho content. © 2011 Elsevier Ltd.


Sheng L.Y.,Peking University | Sheng L.Y.,PKU HKUST ShenZhen Hong Kong Institution | Yang F.,Shenzhen Airlines | Xi T.F.,Peking University | And 2 more authors.
Composites Part B: Engineering | Year: 2011

A copper/aluminum/copper sandwich clad sheet was fabricated by means of cold rolling process and heat treated with different temperature and time. The Al/Cu interface and its bond strength were investigated by SEM, TEM and peeling test. The results reveal that low temperature heat treatment can improve the morphology of Al/Cu interface and increase its bond strength. However high temperature and long time result in the formation of Al2Cu intermetallic compound layer, which is detrimental to the bond strength, and moreover, small Al2O3 particles precipitate along the Al2Cu and Al interface. When the interlayer along Al/Cu interface grows to a certain thickness, the effect of heat treatment temperature and time become weak. For the present study, the reasonable heat treatment may be 423 K and 20 h. © 2011 Elsevier Ltd. All rights reserved.


Ma T.,CAS Shenyang Institute of Metal Research | Ren W.,CAS Shenyang Institute of Metal Research | Liu Z.,CAS Shenyang Institute of Metal Research | Huang L.,Peking University | And 5 more authors.
ACS Nano | Year: 2014

Reducing nucleation density and healing structural defects are two challenges for fabricating large-Area high-quality single-crystal graphene, which is essential for its electronic and optoelectronic applications. We have developed a method involving chemical vapor deposition (CVD) growth followed by repeated etching-regrowth, to solve both problems at once. Using this method, we can obtain single-crystal graphene domains with a size much larger than that allowed by the nucleation density in the initial growth and efficiently heal structural defects similar to graphitization but at a much lower temperature, both of which are impossible to realize by conventional CVD. Using this method with Pt as a growth substrate, we have grown ∼3 mm defect-free single-crystal graphene domains with a carrier mobility up to 13-000 cm2 V-1 s-1 under ambient conditions. © 2014 American Chemical Society.


Lv W.,Tianjin University of Technology | Sun F.,Tianjin University of Technology | Tang D.-M.,CAS Shenyang Institute of Metal Research | Fang H.-T.,Harbin Institute of Technology | And 3 more authors.
Journal of Materials Chemistry | Year: 2011

Hybrid structures combining graphene nanosheets (GNSs) and metal oxide nanoparticles (NPs) are increasingly attracting researchers due to their potential applications in electrochemical energy storage. Such hybrid structures reported thus far are mostly in random organizations of nanosheets anchored with NPs and macroscopically exist in powder aggregates. In this work, a sandwich structure of GNSs and oxide NPs that are macroscopically a free-standing membrane is reported, and a multi-step strategy conducted under "homogenous" and "mild" conditions is developed to ensure the successful fabrication of the membrane-like structure. Both components, tightly fixed NPs and planar GNSs as the skeleton of such sandwich structures, can avoid aggregation or stacking during electrochemical charge-discharge cycling, which effectively maintains the active surface and leaves stable and open channels for ion transport. Such a layered sandwich structure also acts as an ideal strain buffer to accommodate volume changes of the NPs in a fixed direction, and thus has a better resilience and structural stability in the electrochemical charge/discharge process. Hence, such a GNS/NP sandwich structure represents an ideal structure for electrochemical energy storage and a solution for easy manipulation for various applications due to the membrane morphology. © 2011 The Royal Society of Chemistry.


Gao L.,CAS Shenyang Institute of Metal Research | Ren W.,CAS Shenyang Institute of Metal Research | Xu H.,Peking University | Jin L.,CAS Dalian Institute of Chemical Physics | And 8 more authors.
Nature Communications | Year: 2012

Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm2 V-1 s-1 under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications. © 2012 Macmillan Publishers Limited. All rights reserved.


Zhou X.,CAS Shenyang Institute of Metal Research | Zhou X.,Liaoning Institute of Science and Technology | Yang H.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2012

A pentaerythritol glycoside (PG) was synthesized and then its corrosion inhibition for carbon steel in 3.5% NaCl saturated Ca(OH)2 solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), as well as atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Results indicated that the PG compound acted as an anodic inhibitor by strong chemical interaction with the carbon steel surface according to the Langmuir adsorption isotherm. The inhibition efficiency and pitting potential on carbon steel increased with increasing concentrations of the inhibitor. Zero charge potential measurements and quantum chemical calculations provided insight into the inhibition mechanism, which are discussed. © 2011 Elsevier Ltd.


Nie F.L.,Peking University | Wang S.G.,CAS Shenyang Institute of Metal Research | Wang S.G.,CAS International Center for Materials Physics | Wang Y.B.,Peking University | And 2 more authors.
Dental Materials | Year: 2011

Objectives: SUS 304 stainless steels have been widely used in orthodontics and implants such as archwires, brackets, and screws. The purpose of present study was to investigate the biocompatibility of both the commercial microcrystalline biomedical 304 stainless steel (microcrystalline 304ss) and novel-fabricated nanocrystalline 304 stainless steel (nanocrystalline 304ss). Methods: Bulk nanocrystalline 304ss sheets had been successfully prepared by microcrystalline 304ss plates using severe rolling technique. The electrochemical corrosion and ion release behavior immersion in artificial saliva were measured to evaluate the property of biocorrosion in oral environment. The cell lines of murine and human cell lines from oral and endothelial environment were co-cultured with extracts to evaluate the cytotoxicity and provide referential evidence in vivo. Results: The polarization resistance trials indicated that nanocrystalline 304ss is more corrosion resistant than the microcrystalline 304ss in oral-like environment with higher corrosion potential, and the amount of toxic ions released into solution after immersion is lower than that of the microcrystalline 304ss and the daily dietary intake level. The cytotoxicity results also elucidated that nanocrystalline 304ss is biologically compatible in vitro, even better than that of microcrystalline 304ss. Significance: Based on the much higher mechanical and physical performances, nanocrystalline 304ss with enhanced biocorrosion property, well-behaved in vitro cytocompatibility can be a promising alternative in orthodontics and fixation fields in oral cavity. © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.


Tang W.,CAS Shenyang Institute of Metal Research | Su Y.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Water Research | Year: 2013

By doping a proper amount of Mg2+ (~10%) into α-Fe2O3 during a solvent thermal process, ultrafine magnesium ferrite (Mg0.27Fe2.50O4) nanocrystallites were successfully synthesized with the assistance of in situ self-formed NaCl "cage" to confine their crystal growth. Their ultrafine size (average size of ~3.7nm) and relatively low Mg-content conferred on them a superparamagnetic behavior with a high saturation magnetization (32.9emu/g). The ultrafine Mg0.27Fe2.50O4 nanoadsorbent had a high specific surface area of ~438.2m2/g, and demonstrated a superior arsenic removal performance on both As(III) and As(V) at near neutral pH condition. Its adsorption capacities on As(III) and As(V) were found to be no less than 127.4mg/g and 83.2mg/g, respectively. Its arsenic adsorption mechanism was found to follow the inner-sphere complex mechanism, and abundant hydroxyl groups on its surface played the major role in its superior arsenic adsorption performance. It could be easily separated from treated water bodies with magnetic separation, and could be easily regenerated and reused while maintaining a high arsenic removal efficiency. This novel superparamagnetic magnesium ferrite nanoadsorbent may offer a simple single step adsorption treatment option to remove arsenic contamination from water without the pre-/post-treatment requirement for current industrial practice. © 2013 Elsevier Ltd.


Xiong C.,Hainan University | Xiong C.,CAS Shenyang Institute of Metal Research | Deng X.,Hainan University | Deng X.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2010

Well faceted TiO2 nanorods with a regular geometric configuration were hydrothermally prepared by chemical modification of TiCl4 by ethylene glycol to slow down the reactivity of the precursor toward water. XRD patterns revealed that the as made products were pure rutile. The nanorods were highly crystalline and had an elongated prismatic shape. They grew in the [0 0 1] direction and have an aspect ratio of ∼45. The rod size can also be tailored via recipe modification. Ag loaded TiO2 was achieved upon exposure of the rutile nanorods to UV light in AgNO3 aqueous solution. The photocatalytic activities of the pure and Ag loaded TiO2 nanorods were evaluated by the photodegradation of phenol and methylene green (MG). © 2009 Elsevier B.V. All rights reserved.


Cui H.,CAS Shenyang Institute of Metal Research | Su Y.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Water Research | Year: 2013

Highly porous, nanostructured zirconium oxide spheres were fabricated from ZrO2 nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450°C to remove agar network, which provided a simple, low-cost, and safe process for the synthesis of ZrO2 spheres. These ZrO2 spheres had a dual-pore structure, in which interconnected macropores were beneficial for liquid transport and the mesopores could largely increase their surface area (about 98m2/g) for effective contact with arsenic species in water. These ZrO2 spheres demonstrated an even better arsenic removal performance on both As(III) and As(V) than ZrO2 nanoparticles, and could be readily applied to commonly used fixed-bed adsorption reactors in the industry. A short bed adsorbent test was conducted to validate the calculated external mass transport coefficient and the pore diffusion coefficient. The performance of full-scale fixed bed systems with these ZrO2 spheres as the adsorber was estimated by the validated pore surface diffusion modeling. With the empty bed contact time (EBCT) at 10min and the initial arsenic concentration at 30ppb, the number of bed volumes that could be treated by these dry ZrO2 spheres reached ~255,000BVs and ~271,000BVs for As(III) and As(V), respectively, until the maximum contaminant level of 10ppb was reached. These ZrO2 spheres are non-toxic, highly stable, and resistant to acid and alkali, have a high arsenic adsorption capacity, and could be easily adapted for various arsenic removal apparatus. Thus, these ZrO2 spheres may have a promising potential for their application in water treatment practice. © 2013 Elsevier Ltd.


Cui H.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
Journal of Industrial and Engineering Chemistry | Year: 2012

A novel oxide adsorbent of amorphous zirconium oxide (am-ZrO 2) nanoparticles was synthesized by a simple hydrothermal process for effective arsenic removal from aqueous environment. Due to their high specific surface area (327.1m 2/g), large mesopore volume (0.68cm 3/g), and the presence of high affinity surface hydroxyl groups, am-ZrO 2 nanoparticles demonstrated exceptional adsorption performance on both As(III) (arsenite) and As(V) (arsenate) without pre-treatment at near neutral condition. At pH∼7, the adsorption kinetic is fast and the adsorption capacity is high (over 83mg/g for As(III) and over 32.4mg/g for As(V), respectively). Under low equilibrium arsenic concentrations (C e at 0.01mg/L, the maximum contaminant level (MCL) for arsenic in drinking water), the amount of arsenic adsorbed by am-ZrO 2 nanoparticles is over 0.92mg/g for As(III) and over 5.2mg/g for As(V), respectively. The adsorption mechanism of arsenic species onto am-ZrO 2 nanoparticles was found to follow the inner-sphere complex mechanism. Testing with arsenic contaminated natural lake water confirmed the effectiveness of these am-ZrO 2 nanoparticles in removing arsenic from natural water. The immobilized am-ZrO 2 nanoparticles on glass fiber cloth demonstrated an even better arsenic removal performance than dispersed am-ZrO 2 nanoparticles in water, paving the way for their potential applications in water treatment facility to treat arsenic contaminated water body without pre-treatment. © 2012 The Korean Society of Industrial and Engineering Chemistry.


Xu Z.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
Water Research | Year: 2010

Hydrous titanium dioxide (TiO2·xH2O) nanoparticles were synthesized by a low-cost one-step hydrolysis process with aqueous TiCl4 solution. These TiO2·xH2O nanoparticles ranged from 3 to 8 nm and formed aggregates with a highly porous structure, resulting in a large surface area and easy removal capability from aqueous environment after the treatment. Their effectiveness on the removal of As(III) (arsenite) from water was investigated in both laboratory and natural water samples. The adsorption capacity on As(III) of these TiO2·xH2O nanoparticles reached over 83 mg/g at near neutral pH environment, and over 96 mg/g at pH 9.0. Testing with a As(III) contaminated natural lake water sample confirmed the effectiveness of these TiO2·xH2O nanoparticles in removing As(III) from natural water. The high adsorption capacity of the TiO2·xH2O nanoparticles is related to the high surface area, large pore volume, and the presence of high affinity surface hydroxyl groups. © 2010 Elsevier Ltd.


Sun H.,CAS Shenyang Institute of Metal Research | Sun H.,Shanghai JiaoTong University | Wu X.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research | Wei Y.,Shanghai JiaoTong University
Corrosion Science | Year: 2012

The effects of pH and dissolved oxygen (DO) on electrochemical behavior and oxide films of 304SS in borated and lithiated high temperature water were investigated by electrochemical measurements, XPS analysis and SEM technique. An experimental potential-pH diagram for 304SS at 300 °C was constructed. The safe potential-pH zone for minimizing corrosion degradation enlarged in high-pH deaerated solution. As pH increased, the protective property of the oxide films increased, and the concentration of Ni and Fe on film surface declined. The protective property of the oxide films was DO-independent. The related mechanism was discussed. © 2012 Elsevier Ltd.


Xiao D.,Oak Ridge National Laboratory | Yao Y.,CAS Institute of Physics | Yao Y.,University of Texas at Austin | Feng W.,CAS Institute of Physics | And 8 more authors.
Physical Review Letters | Year: 2010

Using first-principles calculations within density functional theory, we explore the feasibility of converting ternary half-Heusler compounds into a new class of three-dimensional topological insulators (3DTI). We demonstrate that the electronic structure of unstrained LaPtBi as a prototype system exhibits a distinct band-inversion feature. The 3DTI phase is realized by applying a uniaxial strain along the [001] direction, which opens a band gap while preserving the inverted band order. A definitive proof of the strained LaPtBi as a 3DTI is provided by directly calculating the topological Z2 invariants in systems without inversion symmetry. We discuss the implications of the present study to other half-Heusler compounds as 3DTI, which, together with the magnetic and superconducting properties of these materials, may provide a rich platform for novel quantum phenomena. © 2010 The American Physical Society.


Li S.,CAS Shenyang Institute of Metal Research | Luo Y.,CAS Institute of Physics | Lv W.,Tianjin University | Yu W.,CAS Shenyang Institute of Metal Research | And 6 more authors.
Advanced Energy Materials | Year: 2011

(VACNTs) are grown directly on a freestanding graphene paper (GP). The desirable carrier transport ability of the VACNTs, good conductivity and mechanical properties of the GP, and strong bonding between the VACNTs and the GP endow the hybrid structure with superior performance when utilized as the electrodes of lithium-ion batteries and dye-sensitized solar cells. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang D.,Xi'an Jiaotong University | Salje E.K.H.,University of Cambridge | Mi S.-B.,Xi'an Jiaotong University | Mi S.-B.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

An effective Hamiltonian scheme is used to reveal the properties of a multidomain structure in BiFeO3 consisting of alternating domains that are initially made of two phases, namely, R3c (ferroelectric with antiphase oxygen octahedral tilting) versus Pnma (antiferroelectric with in-phase and antiphase oxygen octahedral tiltings). These two types of domains dramatically modify their properties as a result of their cohabitation. The weak ferromagnetic vector and polarization rotate, and significantly change their magnitude, in the R3c-like region, while the Pnma-like region becomes polar along the direction of domain propagation. Moreover, the domain walls possess distinct polar and oxygen octahedral tilting patterns that facilitate the transition between these two regions. The studied multidomain is also predicted to exhibit other anomalous properties, such as its strain adopting several plateaus and steps when increasing the magnitude of an applied electric field. © 2013 American Physical Society.


Grushko B.,Jülich Research Center | Mi S.B.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2011

Partial isothermal sections at 810, 700 and 585 °C are presented for a high-Al compositional range of Al-Cu-Mo. The maximal solubility of Cu in the Al 5Mo phase(s) was found to be ∼3 at.%. The previously reported Al 3Ti-type phase was found to be formed around the Al 68.5Cu 6.5Mo 25 composition. The other ternary phase forming in a small compositional range around Al 7Cu 2Mo has a hexagonal structure with a = 0.86796(8) and c = 1.51948(12) nm. © 2010 Elsevier B.V. All rights reserved.


Wang X.,CAS Shenyang Institute of Metal Research | Zhu Y.L.,CAS Shenyang Institute of Metal Research | He M.,CAS Institute of Physics | Lu H.B.,CAS Institute of Physics | Ma X.L.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2011

Erbium oxide (Er2O3) films are well regarded as being suited for high-k replacement of SiO2 in endeavors to further miniaturize and enhance the performance of microelectronics. Er 2O3 films were deposited on Si (0 0 1) substrates by laser molecular beam epitaxy. The structures and microstructures of the films and the interfacial layers were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results from the XRD and selected area electron diffractions of Er2O3 films with thicknesses of 30 and 100 nm indicate that the films are polycrystalline, with dominant (1 1 1) textures of Er2O3 {1 1 1} // Si (0 0 1). Amorphous layers dotted with small ordered islands were observed and confirmed to be located at the interfaces between the films and the Si substrates with dark-field image and high-resolution TEM. High-resolution Z-contrast imaging, energy dispersive X-ray spectroscopy and energy-filtered imaging were applied to identify the compositions of the interfacial layers. The salient feature is that the layers consist primarily of Er and O, with a very small amount of Si. This kind of Er-O-based interface layer may play a very important role in the electrical and optical properties of the films. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Xu L.-P.,GuangZhou Research Institute of Nonferrous Metals | Zhang E.-L.,Jiamusi University | Yang K.,CAS Shenyang Institute of Metal Research
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

Calcium phosphate coated Mg alloy was prepared. The phase constitute and surface morphology were identified and observed by X-ray diffractometer (XRD) and SEM. The results show that the coating is composed of flake-like CaHPO 4·2H 2O crystals. The corrosion resistance of the coated Mg alloy was measured by electrochemical polarization and immersion test in comparison with uncoated Mg alloy. Cytocompatibility was designed by observing the attachment, growth and proliferation of L929 cell on both coated and uncoated Mg alloy samples. The results display that the corrosion resistance of the coated Mg alloy is better than that of uncoated one. The immersion test also shows that the calcium phosphate coating can mitigate the corrosion of Mg alloy substrate, and tends to transform into hydroxyapatite (HA). Compared with uncoated Mg alloy, L929 cells exhibit good adherence, growth and proliferation characteristics on the coated Mg alloy, indicating that the cytocompatibility is significantly improved with the calcium phosphate coating.


Liu L.,CAS Shenyang Institute of Metal Research | Yang W.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2014

A novel Cu2O/TiO2 composite photocatalyst structure of Cu2O nanospheres decorated with TiO2 nanoislands were synthesized by a facile hydrolyzation reaction followed by a solvent-thermal process. In this Cu2O/TiO2 composite photocatalyst, Cu2O served as the main visible light absorber, while TiO2 nanoislands formed heterojunctions of good contact with Cu2O, beneficial to the photoexcited electron transfer between them. Their band structure match and inner electrostatic field from the p-n heterojunction both favored the transfer of photoexcited electrons from Cu2O to TiO 2, which effectively separated the electron-hole pairs. Photogenerated holes on Cu2O could react with water or organic pollutants/microorganisms in water to avoid accumulation on Cu2O because of the partial TiO2 nanoislands coverage, which enhanced their stability during the photocatalysis process. Their superior photocatalytic performance under visible light illumination was demonstrated in both the degradation of methyl orange and the disinfection of Escherichia coli bacteria. An interesting post-illumination catalytic memory was also observed for this composite photocatalyst as demonstrated in the disinfection of Escherichia coli bacteria in the dark after the visible light was shut off, which could be attributed to the transfer of photoexcited electrons from Cu2O to TiO2 and their trapping on TiO2 under visible light illumination, and their release in the dark after the visible light was shut off. © 2014 American Chemical Society.


Mi S.-B.,Jülich Research Center | Mi S.-B.,CAS Shenyang Institute of Metal Research
Thin Solid Films | Year: 2011

Thin films of SrCuO2 with tetragonal structure have been epitaxially grown on SrTiO3 (001) substrates by high-oxygen pressure sputtering technique. The interface structure between SrCuO2 and SrTiO3 and configuration of defects in SrCuO2 thin films have been characterized by means of high-resolution transmission electron microscopy. Two types of film-substrate interface structure coexist and are determined as bulk-SrO-TiO2-Sr(O) -CuO2-Sr-bulk and bulk-SrO-TiO2-SrO-Sr(O) -CuO2-Sr-bulk. The planar faults with double SrO atomic layers in {100} planes in SrCuO2 thin films are observed, which mainly arise from the coalescence of these two types of film-substrate interface structure. Meanwhile, planar faults in {110} planes are observed in thin films and structural models are proposed. © 2010 Elsevier B.V. All rights reserved.


Liu Z.Q.,CAS Shenyang Institute of Metal Research | Wang W.H.,CAS Institute of Physics | Jiang M.Q.,CAS Institute of Mechanics | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Philosophical Magazine Letters | Year: 2014

The energetic driving force and resistance for shearing and cracking in metallic glasses (MGs) are quantitatively evaluated. A universal thermodynamic criterion is proposed for better understanding the intrinsic correlations between fracture toughness and Poissons ratio, the competitions between various deformation modes and the ductile-to-brittle transition in MGs and other materials. A new cooperation parameter δ is also introduced to depict quantitatively the relative propensity of shearing versus cracking. This work could provide insights into the long-standing issues of deformation mechanisms of glassy materials, and be helpful in searching for ductile and tough MGs. © 2014 © 2014 Taylor & Francis.


Wang Z.,CAS Institute of Physics | Sun Y.,CAS Shenyang Institute of Metal Research | Chen X.-Q.,CAS Shenyang Institute of Metal Research | Franchini C.,CAS Shenyang Institute of Metal Research | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Three-dimensional (3D) Dirac point, where two Weyl points overlap in momentum space, is usually unstable and hard to realize. Here we show, based on the first-principles calculations and effective model analysis, that crystalline A 3Bi (A=Na, K, Rb) are Dirac semimetals with bulk 3D Dirac points protected by crystal symmetry. They possess nontrivial Fermi arcs on the surfaces and can be driven into various topologically distinct phases by explicit breaking of symmetries. Giant diamagnetism, linear quantum magnetoresistance, and quantum spin Hall effect will be expected for such compounds. © 2012 American Physical Society.


Tang W.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
Journal of Hazardous Materials | Year: 2011

Ultrafine iron oxide (α-Fe2O3) nanoparticles were synthesized by a solvent thermal process and used to remove arsenic ions from both lab-prepared and natural water samples. The α-Fe2O3 nanoparticles assumed a near-sphere shape with an average size of about 5nm. They aggregated into a highly porous structure with a high specific surface area of ∼162m2/g, while their surface was covered by high-affinity hydroxyl groups. The arsenic adsorption experiment results demonstrated that they were effective, especially at low equilibrium arsenic concentrations, in removing both As(III) and As(V) from lab-prepared and natural water samples. Near the neutral pH, the adsorption capacities of the α-Fe2O3 nanoparticles on As(III) and As(V) from lab-prepared samples were found to be no less than 95mg/g and 47mg/g, respectively. In the presence of most competing ions, these α-Fe2O3 nanoparticles maintained their arsenic adsorption capacity even at very high competing anion concentrations. Without the pre-oxidation and/or the pH adjustment, these α-Fe2O3 nanoparticles effectively removed both As(III) and As(V) from a contaminated natural lake water sample to meet the USEPA drinking water standard for arsenic. © 2011 Elsevier B.V.


Sun W.,CAS Shenyang Institute of Metal Research | Sun W.,Hefei University of Technology | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

A novel quasi-monodisperse, superparamagnetic Pd/Fe3O 4 catalyst was synthesized for effective catalytic bromate reduction. The catalyst was prepared by dispersing nanoparticles of Pd (weight percent up to 1%) on the surface of superparamagnetic Fe3O4 microspheres with 300-500 nm in diameter and 10-20 nm in grain size. Complete reduction of bromate by this Pd/Fe3O4 catalyst was demonstrated within a short period (<2 h) over a range of pH values, in the presence of a variety of co-existing ions, and after multiple cycles. In addition, the superparamagnetic nature of the catalyst enhanced its good dispersion in water during water treatment when there was no external magnetic field, and its high saturation magnetization allowed an easy magnetic separation from water when an external magnetic field was applied after the water treatment. Thus, it could be easily recycled and reused, further enhancing its application potential. © 2013 The Royal Society of Chemistry.


Tang W.,CAS Shenyang Institute of Metal Research | Su Y.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Ultrafine superparamagnetic magnesium ferrite nanocrystallites were successfully synthesized by doping Mg2+ into α-Fe 2O3 in a solvent thermal process. The dopant altered the microstructure of the α-Fe2O3 which resulted in an enhanced arsenic adsorption performance and an easy magnetic separation capability. At a concentration of 10%, Mg-doping largely increased the surface area to ∼438 m2 g-1, enhanced the dispersion and contact with arsenic species in water due to its superparamagnetic behavior, and largely improved the arsenic adsorption performance in both lab-prepared and natural water samples at near neutral pH when compared with ultrafine α-Fe2O3 nanoparticles. At an Mg concentration of 10%, the amounts of As(iii) and As(v) adsorbed reached 9.3 mg g-1 and 10 mg g-1, respectively, at a low equilibrium arsenic concentration of less than 10 μg L-1. The nanocrystallites could be easily separated from water when an external magnetic field was present after water treatment due to their high saturation magnetization, which solved the potential nanomaterial dispersion problem and facilitated arsenic desorption and reuse of the material. This journal is © 2013 The Royal Society of Chemistry.


Wang D.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Wang Q.Z.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,Shanghai JiaoTong University
Materials and Design | Year: 2013

Sixmilimeter thick hot-rolled SiCp/2009Al composite plates were successfully joined by friction stir welding (FSW) using an ultra-hard material tool. After FSW, the distribution of the SiC particles in the nugget zone (NZ) was more homogeneous than that in the base material (BM). Scanning electron microscopic examinations (SEM) and X-ray analysis (XRD) indicated that part of the Al2Cu was dissolved into the aluminum matrix in the NZ due to intense plastic deformation and high temperature during FSW. The undissolved Al2Cu particles remained in the NZ and coarsened during the cooling process after FSW. The ultimate tensile strength (UTS) of the as-welded joint is only 321MPa and failed in the BM zone due to the low strength of the BM. After T4 heat treatment, the strength of the joint increased and became close to that of the BM with T4 temper, because most of the Al2Cu particles were dissolved into the matrix and re-precipitated homogeneously as the GP zones, which are the major strengthening precipitates for T4-tempered 2009Al alloy. © 2012 Elsevier Ltd.


Li F.,Japan National Institute of Advanced Industrial Science and Technology | Li F.,University of Tokyo | Chen Y.,Japan National Institute of Advanced Industrial Science and Technology | Chen Y.,Hainan University | And 8 more authors.
Energy and Environmental Science | Year: 2014

Ru nanoparticles have been deposited onto a multi-walled carbon nanotube paper (Ru@MWCNTP) via a wet chemical method. The resulting catalyst, Ru@MWCNTP has been demonstrated to significantly reduce the charge overpotentials of the Li-O2 battery at a current density of 500 mA g-1. The reversible formation and decomposition of Li2O2 can be revealed by X-ray diffraction (XRD). In the initial 20 cycles of discharge and charge, the Li-O2 battery with Ru@MWCNTP presents a stable capacity of 5000 mA h g-1 and an almost constant discharge-charge potential, contrasting with the quickly decaying capacity of the bare MWCNTP without the addition of Ru nanoparticles. The combination of the porous networks of the multi-walled carbon nanotubes (MWCNTs), which are beneficial for the facile transport of both electrons and oxygen, and the superior catalytic activity of Ru nanoparticles enables a good cycling performance and rate capability of the Li-O2 battery. This journal is © 2014 the Partner Organisations.


Du K.,Case Western Reserve University | Du K.,CAS Shenyang Institute of Metal Research | Ernst F.,Case Western Reserve University | Pelsozy M.C.,Case Western Reserve University | And 2 more authors.
Acta Materialia | Year: 2010

We study the atomistic structure of Pt catalyst nanoparticles using HRTEM (high-resolution transmission electron microscopy). The particles exhibit a faceted, cubo-octahedral shape, extended planar defects, and mono-atomic surface steps. HRTEM imaging with negative spherical aberration yielded atomic-resolution images with a minimum of artifacts. Combining digital image processing, quantitative image analysis, and HRTEM image simulations to determine local variations of the spacing between neighboring Pt atom columns, we have found an expansion of the lattice parameter in the particle core and even larger, locally varying expansion of Pt-Pt next-neighbor distances at the particle surface. The latter likely originates from an amorphous oxide on the nanoparticle surface and/or dissolution of oxygen on subsurface sites. These structural features may significantly impact the catalytic activity of Pt nanoparticles. © 2009 Acta Materialia Inc.


Li Q.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
Environmental Science and Technology | Year: 2010

A novel composite photocatalyst of nitrogen (N) and fluorine (F) codoped titanium oxide (TiO2) nanotube arrays with dispersed palladium oxide (PdO) nanoparticles was developed by dispersing PdO nanoparticles into N and F codoped TiO2 nanotube array template created by anodization of titanium foil. These N and F codoped TiO2/PdO nanotube arrays demonstrated increased visible light absorption, fast superhydrophilicity conversion, and enhanced photocatalytic degradation of organic pollutants. The enhancement on the photocatalytic performance was explained by the optoelectronic coupling between dispersed PdO nanoparticles and N and F codoped TiO2 nanotube arrays under visible light illumination, which involves trapping of electrons by PdO nanoparticles, and subsequently decreases the electron/hole pair recombination. Various transition metal/metal oxide nanoparticles could be introduced into nanotube arrays by this simple approach, which could create novel properties for nanotube arrays and promise a wide range of technical applications. © 2010 American Chemical Society.


Sun Z.,CAS Shenyang Institute of Metal Research | Sun Z.,University of Wollongong | Li M.,CAS Shenyang Institute of Metal Research | Zhou Y.,CAS Shenyang Institute of Metal Research | Zhou Y.,Aerospace Research Institute of Materials And Processing Technology
International Materials Reviews | Year: 2014

Yttrium silicates (Y-Si-O oxides), including Y2Si2O7, Y2SiO5, and Y4·67(SiO4)3O apatite, have attracted wide attentions from material scientists and engineers, because of their extensive polymorphisms and important roles as grain boundary phases in improving the high-temperature mechanical/thermal properties of Si3N4and SiC ceramics. Recent interest in these materials has been renewed by their potential applications as high-temperature structural ceramics, oxidation protective coatings, and environmental barrier coatings (EBCs). The salient properties of Y-Si-O oxides are strongly related to their unique chemical bonds and microstructure features. An in-depth understanding on the synthesis - multi-scale structure-property relationships of the Y-Si-O oxides will shine a light on their performance and potential applications. In this review, recent progress of the synthesis, multi-scale structures, and properties of the Y-Si-O oxides are summarised. First, various methods for the synthesis of Y-Si-O ceramics in the forms of powders, bulks, and thin films/coatings are reviewed. Then, the crystal structures, chemical bonds, and atomic microstructures of the polymorphs in the Y-Si-O system are summarised. The third section focuses on the properties of Y-Si-O oxides, involving the mechanical, thermal, dielectric, and tribological properties, their environmental stability, and their structure-property relationships. The outlook for potential applications of Y-Si-O oxides is also highlighted. © 2014 Institute of Materials, Minerals and Mining and ASM International.


He Q.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign | Ma E.,Johns Hopkins University | Xu J.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2012

For the emerging bulk metallic glasses (BMGs), damage tolerance is a key mechanical property needed for their practical applications. To reach a fracture toughness on a par with, or even better than, conventional engineering alloys, the only route reported so far is to compositionally base the BMG on high-cost palladium (Pd), which has a very high Poisson's ratio (∼0.42). Here we report the discovery of a Zr 61Ti 2Cu 25Al 12 (ZT1) BMG that has a toughness as high as the Pd-based BMG, but at the same time consists of common engineering metals and has robust glass-forming ability. The new BMG, while having an unimpressive Poisson's ratio of 0.367, derives its high toughness from its high propensity for crack deflection and local loading-mode change at the crack tip due to extensive shear band interactions. The crack-resistance curve (R-curve) of this BMG has been obtained from fatigue pre-crack samples, employing standard "single- specimen" and "multiple-specimen" techniques. © 2012 Acta Materialia Inc. Published by Elsevier Ltd.


Liu L.,CAS Shenyang Institute of Metal Research | Yang W.,CAS Shenyang Institute of Metal Research | Sun W.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2015

The creation of photocatalysts with controlled facets has become an important approach to enhance their activity. However, how the formation of heterojunctions on exposed facets could affect their photocatalytic performance ranking had not yet been investigated. In this study, Cu2O@TiO2 core-shell structures were created, and Cu2O/TiO2 p-n heterojunctions were formed on various exposed facets of Cu2O cubes, Cu2O cuboctahedra, and Cu2O octahedra, respectively. These Cu2O@TiO2 polyhedra demonstrated an enhanced photocatalytic degradation effect on Methylene Blue (MB) and 4-nitrophenol (4-NP) under visible light illumination, because of the enhanced charge carrier separation by the formation of Cu2O@TiO2 p-n heterojunctions. It was further found that their photocatalytic performance was also facet-dependent as pure Cu2O polyhedra, while the photocatalytic performance ranking of these Cu2O@TiO2 polyhedra was different with that of their corresponding Cu2O polyhedron cores. By the combination of optical property measurement and XPS analysis, the energy band alignments of these Cu2O@TiO2 polyhedra were determined, which demonstrated that Cu2O@TiO2 octahedra had the highest band offset for the separation of charge carriers. Thus, the charge-carrier-separation-driven force in Cu2O@TiO2 polyhedra was different from their corresponding Cu2O polyhedron cores, which resulted in their different surface photovoltage spectrum (SPS) responses and different photocatalytic performance rankings. © 2014 American Chemical Society.


Hang C.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
Industrial and Engineering Chemistry Research | Year: 2012

Hydrous zirconium oxide (ZrO 2̇xH 2O) were synthesized by a low-cost hydrothermal process followed with heat treatment. ZrO 2·xH 2O nanoparticles ranged from 6 nm to 10 nm and formed highly porous aggregates, resulting in a large surface area of 161.8 m 2 g -1. The batch tests on the laboratory water samples demonstrated a very high degree of As(III) and As(V) removal by ZrO 2̇xH 2O nanoparticles. The adsorption mechanism study demonstrated that both arsenic species form inner-sphere surface complexes on the surface of ZrO 2̇xH 2O nanoparticles. Higher arsenic removal effect of these ZrO 2̇xH 2O nanoparticles were demonstrated, compared with commercially available Al 2O 3 and TiO 2 nanoparticles. Ionic strength and competing ion effects on the arsenic adsorption of these ZrO 2xH 2O nanoparticles were also studied. Testing with natural lake water confirmed the effectiveness of ZrO 2·xH 2O nanoparticles in removing arsenic species from natural water, and the immobilization of ZrO 2̇ xH 2O nanoparticles on glass fiber cloth minimized the dispersion of nanoparticles into the treated body of water. The high adsorption capacity of ZrO 2̇xH 2O nanoparticles is shown to result from the strong inner-sphere surface complexing promoted by the high surface area, large pore volume, and surface hydroxyl groups of zirconium oxide nanoparticles. © 2011 American Chemical Society.


Obot I.B.,University of Uyo | Obi-Egbedi N.O.,University of Ibadan | Umoren S.A.,University of Uyo | Umoren S.A.,CAS Shenyang Institute of Metal Research | Ebenso E.E.,North West University South Africa
International Journal of Electrochemical Science | Year: 2010

The extract of Ipomoea invulcrata (IP) has been studied as a possible source of green inhibitor for corrosion of aluminium in 1M HCl at 30-60 °C using the conventional weight loss technique. The studies reveal that at constant acid concentration, the plant extract acts as an effective inhibitor for aluminium corrosion in acidic medium. Inhibition efficiency increases with concentration but decreases with increase in temperature and immersion time. The enhancement of inhibition efficiency of IP with the addition of KI and KSCN has also been studied. The apparent activation energy and the thermodynamic parameters governing the corrosion process have also been calculated. The adsorption of IP was in accord with the Langmuir adsorption isotherm at all the temperature studied. The mechanism of physical adsorption is proposed for the inhibitory action of IP and is satisfactorily explained by both kinetic and thermodynamic parameters. © 2010 by ESG.


Sun W.,CAS Shenyang Institute of Metal Research | Sun W.,University of Science and Technology of China | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2012

A magnetite supported monometallic Pd catalyst was synthesized by a co-precipitation process followed with the reduction in pure hydrogen at 453K. The catalyst was composed of ultrafine Pd nanoparticles (∼2nm) highly dispersed on the surface of superparamagnetic Fe 3O 4 nanoparticles. Aside from its roles as the catalyst support and the magnetic separation medium, Fe 3O 4 was found to be a good promoter for the nitrate reduction, where nitrate was firstly reduced to nitrite by the Fe(II)/Fe(III) redox couple, and subsequently reduced to nitrogen and ammonium. Further mechanistic studies demonstrated that besides the Pd sites, active sites for the nitrite reduction also exist on the surface of Fe 3O 4. Part of the nitrite reduction occurred on the surface of Fe 3O 4, which may also be attributed to the Fe(II)/Fe(III) redox couple. In the present study, ammonium was the main product because of the different denitrification mechanisms compared with bimetallic catalysts. © 2012 Elsevier B.V.


Lu S.,KTH Royal Institute of Technology | Hu Q.-M.,CAS Shenyang Institute of Metal Research | Johansson B.,KTH Royal Institute of Technology | Johansson B.,Uppsala University | And 3 more authors.
Acta Materialia | Year: 2011

The alloying effects of Mn, Co and Nb on the stacking fault energy (SFE) of austenitic stainless steels, Fe-Cr-Ni with various Ni contents, are investigated via quantum-mechanical first-principles calculations. In the composition range (cCr = 20%, 8 ≤ cNi ≤ 20%, 0 ≤ cMn, cCo, cNb ≤ 8%, balance Fe) studied here, it is found that Mn always decreases the SFE at 0 K but increases it at room temperature in high-Ni (cNi ≳ 16%) alloys. The SFE always decreases with increasing Co content. Niobium increases the SFE significantly in low-Ni alloys; however, this effect is strongly diminished in high-Ni alloys. The SFE-enhancing effect of Ni usually observed in Fe-Cr-Ni alloys is inverted to an SFE-decreasing effect by Nb for cNb ≳ 3%. The revealed nonlinear composition dependencies are explained in terms of the peculiar magnetic contributions to the total SFE. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Liu Y.,CAS Shenyang Institute of Metal Research | Li Q.,CAS Shenyang Institute of Metal Research | Gao S.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research | Shang J.K.,University of Illinois at Urbana - Champaign
CrystEngComm | Year: 2014

Well-defined WO3·H2O hollow spheres composed of nanoflakes were successfully synthesized by a template-free solvothermal process with i-PrOH-H2O mixture solvent. In this process, the tungsten precursor was firstly hydrolyzed to form solid spheres composed of both WO3·2H2O and WO3·H2O phases. Then, these solid spheres underwent an Ostwald ripening process and the WO3·2H2O phase was dehydrated to WO 3·H2O at the same time to form hollow spheres with a pure WO3·H2O phase. With appropriate calcination temperature, hollow spheres with WO3 (major) and WO 3·H2O (minor) mixture phases were created. These hollow spheres with WO3 and WO3·H2O mixture phases demonstrated a largely enhanced photocatalytic activity for RhB degradation under visible light irradiation compared with either pure WO 3·H2O hollow spheres or pure WO3 hollow spheres which could be attributed to the matched band structure between the WO3 and WO3·H2O phases. Thus, an effective charge carrier separation can occur between the WO3 and WO3·H2O phases of these hollow spheres under visible light irradiation, contributing to the observed largely enhanced photocatalytic performance. This journal is © the Partner Organisations 2014.


Wang L.,Beihang University | Shang J.-X.,Beihang University | Wang F.-H.,Capital Normal University | Chen Y.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Acta Materialia | Year: 2013

We have constructed the surface phase diagrams for oxygen adsorption on γ-TiAl low-index surfaces using density-functional theory calculations. From these surface phase diagrams, the selective oxidation behaviors of the γ-TiAl surfaces and the corresponding polycrystalline systems can be easily understood and predicted. For the (1 0 0) surface, complete selective oxidation of titanium is favored and a titanium oxide layer may be produced at the initial stage of oxidation. For the (1 1 0) and (0 0 1) surfaces, only titanium oxides may form. For the γ-TiAl polycrystalline system, O may induce complete Ti and Al surface segregations on the Ti-rich and Al-rich conditions, respectively. In addition, the microscopic oxidation mechanisms are identified and the experimental results are successfully explained. More importantly, by comparing the different TiAl surface orientations, a comprehensive surface phase diagram is constructed to study the oxidation behaviors of polycrystalline γ-TiAl. This method can also be applied to other polycrystalline materials. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Shao L.,Fritz Haber Institute of the Max Planck Society | Zhang B.,Fritz Haber Institute of the Max Planck Society | Zhang B.,CAS Shenyang Institute of Metal Research | Zhang W.,Fritz Haber Institute of the Max Planck Society | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2013

More than scratching the surface: The mechanism by which supported Pd nanoparticles (PdNPs) catalyze cross-coupling reactions is the subject of debate. The changes in supported PdNPs during coupling reactions are studied by exploiting modified carbon nanotubes (CNTs) as support materials. After catalysis, CNTs with scratched walls and PdNPs with surface crystalline distortions were discovered, offering insights into the catalytic mechanism. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zeng R.-C.,Shandong University of Science and Technology | Zeng R.-C.,CAS Shenyang Institute of Metal Research | Hu Y.,Shandong University of Science and Technology | Guan S.-K.,Zhengzhou University | And 2 more authors.
Corrosion Science | Year: 2014

The effects of anions in saline solutions on the corrosion behaviour of magnesium alloy AZ31 were investigated using hydrogen evolution, pH and potentiodynamic measurements. The results demonstrated that adding bicarbonate and sulphate ions to saline solution accelerated the corrosion, whereas hydrogen phosphate and dihydrogen phosphate retarded the corrosion and decreased the open-circuit potentials. A model involving the magnesium hydroxide and magnesium carbonate film formation mechanism was proposed. The change in the solution pH over time did not reflect the corrosion rates of the magnesium alloys due to the influence of anions. © 2014 Elsevier Ltd.


Liu H.,CAS Shenyang Institute of Metal Research | Zhang L.,CAS Shenyang Institute of Metal Research | Wang N.,Hong Kong University of Science and Technology | Su D.S.,CAS Shenyang Institute of Metal Research
Angewandte Chemie - International Edition | Year: 2014

The highly efficient preparation of metal nanoparticles embedded in a carbon nanotube remains a considerable challenge. Herein, we report a simple and templatebased procedure for the fabrication of carbon nanotubes with Pd nanoparticles uniformly embedded in the inner carbon surfaces. In addition to the novel structure, the sinter-resistance of the as-prepared Pd/C nanocomposite was much better than that of the traditional carbon-nanotube-supported Pd catalysts. The as-prepared Pd/C nanocomposite has a high recyclability in a liquid-phase Suzuki coupling reaction. This strategy may be extended as a general approach to prepare metal nanoparticles supported on carbon-nanotubes. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wei S.,Angang Steel | Wei S.,CAS Shenyang Institute of Metal Research | Lu S.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2012

A low carbon microalloyed S355 steel weld metal with and without Nb addition was subjected to normalizing process for different times and the microstructure as well as mechanical properties of the weld metal were evaluated and analyzed. The results showed that there were great differences between the microstructure and mechanical properties of the as-welded and the as-normalized weld metal, and the number of normalizing times played an important role on the microstructure and properties of the Nb bearing weld metal. The strength and plasticity of the as-welded weld metal were improved with the addition of Nb element, while the impact toughness was not affected significantly with the Nb addition. The normalizing treatment at 900 °C converted the columnar grain microstructure (CGZ) of weld metal in the as-welded state to an equiaxed grain structure, and the NbC precipitates were observed in the CGZ of the Nb bearing weld metal. The as-normalized weld metal had lower yield and tensile strength, higher elongation and impact energy than the as-welded weld metal. Different normalizing times were performed in order to study the effect of subsequent normalizing on the mechanical properties of the weld metal. With increase of the normalizing times at the normalizing temperature of 900 °C for 3. h, the size of NbC precipitates in the Nb bearing weld metal increased significantly, while the strength, elongation and impact energy first increased and then decreased. After three normalizing treatments, the optimal microstructure, strength, plasticity and toughness of the weld metal were obtained. After six normalizing processes, a duplex grain structure appeared, which deteriorated the properties of the Nb bearing weld metal. However, for the Nb free weld metal, the microstructure and mechanical properties did not change significantly with increasing normalizing times. © 2011 Elsevier Ltd.


Zheng H.,University of Pittsburgh | Zheng H.,Wuhan University | Cao A.,Northwestern University | Weinberger C.R.,Sandia National Laboratories | And 6 more authors.
Nature Communications | Year: 2010

Although deformation processes in submicron-sized metallic crystals are well documented, the direct observation of deformation mechanisms in crystals with dimensions below the sub-10-nm range is currently lacking. Here, through in situ high-resolution transmission electron microscopy (HRTEM) observations, we show that (1) in sharp contrast to what happens in bulk materials, in which plasticity is mediated by dislocation emission from Frank-Read sources and multiplication, partial dislocations emitted from free surfaces dominate the deformation of gold (Au) nanocrystals; (2) the crystallographic orientation (Schmid factor) is not the only factor in determining the deformation mechanism of nanometre-sized Au; and (3) the Au nanocrystal exhibits a phase transformation from a face-centered cubic to a body-centered tetragonal structure after failure. These findings provide direct experimental evidence for the vast amount of theoretical modelling on the deformation mechanisms of nanomaterials that have appeared in recent years. © 2010 Macmillan Publishers Limited. All rights reserved.


Zhang X.,CAS Shenyang Institute of Metal Research | Zhao J.,CAS Shenyang Institute of Metal Research | Jiang H.,CAS Shenyang Institute of Metal Research | Zhu M.,Nanjing Southeast University
Acta Materialia | Year: 2012

A three-dimensional (3-D) cellular automaton model for dendritic growth in multi-component alloys is developed. The velocity of advance of the solid/liquid (S/L) interface is calculated using the solute conservation relationship at the S/L interface. The effect of interactions between the alloying elements on the diffusion coefficient of solutes in the solid and liquid phases are considered. The model is first validated by comparing with the theoretical predictions for binary and ternary alloys, and then applied to simulate the solidification process of Al-Cu-Mg alloys by a coupling of thermodynamic and kinetic calculations. The numerical results obtained show both the free dendrite growth process as well as the directional solidification process. The calculated secondary dendrite arm spacing in the directionally solidified Al-Cu-Mg alloy is in good agreement with the experimental results. The effect of interactions between the various alloying elements on dendritic growth is discussed. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Shao L.-H.,TU Hamburg - Harburg | Shao L.-H.,Karlsruhe Institute of Technology | Biener J.,Lawrence Livermore National Laboratory | Jin H.-J.,Karlsruhe Institute of Technology | And 5 more authors.
Advanced Functional Materials | Year: 2012

A novel nanoporous carbon/electrolyte hybrid material is reported for use in actuation. The nanoporous carbon matrix provides a 3D network that combines mechanical strength, light weight, and low cost with an extremely high surface area. In contrast to lower dimensional nanomaterials, the nanoporous carbon matrix can be prepared in the form of macroscopic monolithic samples that can be loaded in compression. The hybrid material is formed by infiltrating the free internal pore volume of the carbon with an electrolyte. Actuation is prompted by polarizing the internal interfaces via an applied electric bias. It is found that the strain amplitude is proportional to the Brunauer-Emmett-Teller (BET) mass specific surface area, with reversible volume strain amplitudes up to the exceptionally high value of 6.6%. The mass-specific strain energy density compares favorably to reported values for piezoceramics and for nanoporous metal actuators. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zeng R.,Shandong University of Science and Technology | Zeng R.,CAS Shenyang Institute of Metal Research | Han E.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
International Journal of Fatigue | Year: 2012

Effect of loading frequency on the fatigue crack propagation (FCP) rate and mechanism of extruded Mg-Al-Zn alloys is discussed. The results demonstrate that the FCP rate of AZ80 and AZ61 alloys increases with reducing frequency. The frequency has a more significant influence on FCP rate of the AZ80 alloy than that of the AZ61 alloy. This scenario may be attributed to the thickness of the oxide films on the fracture surfaces, strain rate and the microstructure. A model based on the Langmuir and BET equation is established to predict the thickness of the oxidation films on the fracture surfaces. © 2011 Published by Elsevier Ltd.


Villa A.,University of Milan | Wang D.,Karlsruhe Institute of Technology | Su D.S.,Fritz Haber Institute of the Max Planck Society | Su D.S.,CAS Shenyang Institute of Metal Research | Prati L.,University of Milan
Catalysis Science and Technology | Year: 2015

Since the discovery of the peculiar catalytic activity of gold catalysts, it became clear that gold could play a fundamental role also as a modifier. Indeed, more active catalysts such as those based on Pd or Pt showed specific and sometimes unexpected properties when modified with gold. This paper reviews advances in the field of Au-based bimetallic catalysts with particular attention to their preparation, characterization and catalytic activity. AuPd catalysts, the most widely studied, have been chosen as an example to show how the different obtained morphologies (alloy, core-shell, decorated particles) can contribute to the catalytic activity. © The Royal Society of Chemistry 2015.


Chen S.,CAS Hefei Key Laboratory of Materials for Energy Conversion | Zhang B.,CAS Shenyang Institute of Metal Research | Su D.,CAS Shenyang Institute of Metal Research | Huang W.,CAS Hefei Key Laboratory of Materials for Energy Conversion
ChemCatChem | Year: 2015

Employing anatase TiO2 nanocrystals with predominantly {001} facets, anatase TiO2 nanocrystals with predominantly {100} facets, and TiO2 P25 with predominantly {101} facets as supports, we have comprehensively studied the morphology effect of TiO2 on the Au-TiO2 interaction, structure, and catalytic performance of Au/TiO2 catalysts in C3H6 epoxidation with H2 and O2, C3H6 oxidation with O2, and H2 oxidation. A strong morphology-dependent interplay between the Au-TiO2 interaction and the catalyst structure was observed. Only Au nanoparticles were present in the Au/TiO2 catalysts and the Auδ- species was the largest in Au/TiO2{001} due to the creation of surface O vacancies of TiO2{001} upon Au loading, whereas the fraction of Auδ+ species was largest in Au/TiO2{100} due to the preserved surface stoichiometry of TiO2{100} upon Au loading. In H2 oxidation, Au/TiO2{100} with the largest fraction of Auδ+ species was the most active but least selective toward H2O2, whereas Au/TiO2{001} with the largest fraction of Auδ- species was the most selective toward H2O2. In C3H6 oxidation with O2, tiny C3H6 conversions with the formation of partial oxidation products were observed at low temperatures, whereas C3H6 combustion occurred at high temperatures. In C3H6 epoxidation with O2 and H2, the ensemble consisting of closely connected Auδ- and Ti4+ on anatase TiO2{001} and {101} facets with weak adsorption ability was the active structure and the Au/TiO2{001} catalyst containing the largest amount of this ensemble was the most active. These results demonstrated morphological engineering of oxides as an effective strategy to optimize the catalytic performance and understand the fundamentals of catalysis involving oxides. Titania mania: The Au-TiO2 interaction, structure and catalytic performance of Au/TiO2 catalysts in C3H6 epoxidation with H2 and O2, C3H6 oxidation, and H2 oxidation strongly depend on the TiO2 morphology. In the epoxidation, the ensemble of closely connected Auδ- and Ti4+ on anatase TiO2{001} and {101} facets with weak adsorption ability is the active structure and the Au/TiO2{001} catalyst containing the largest amount of the Auδ--Ti4+ ensemble is the most active. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu Z.Q.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Journal of Applied Physics | Year: 2014

There exist general conflicts between strength and toughness in crystalline engineering materials, and various strengthening and toughening strategies have been developed from the dislocation motion perspectives. Metallic glasses (MGs) have demonstrated great potentials owing to their unique properties; however, their structural applications are strictly limited. One of the key problems is that the traditional strengthening and toughening strategies and mechanisms are not applicable in MGs due to the absence of dislocations and crystalline microstructures. Here, we show that the strength and toughness, or equivalently the shear modulus and Poisson's ratio, are invariably mutually exclusive in MGs. Accordingly, the MGs can be categorized into four groups with different levels of integrated mechanical properties. It is further revealed that the conflicts originate fundamentally from the atomic bonding structures and the levels of strength-toughness combinations are indeed dominated by the bulk modulus. Moreover, we propose novel strategies for optimizing the mechanical properties of MGs from the elastic perspectives. We emphasize the significance of developing high bulk modulus MGs to achieve simultaneously both high strength and good toughness and highlight the elastic opportunities for strengthening and toughening materials. © 2014 AIP Publishing LLC.


Yang Z.,CAS Shenyang Institute of Metal Research | Yang Z.,Oak Ridge National Laboratory | Yang Z.,University of Tennessee at Knoxville | Chisholm M.F.,Oak Ridge National Laboratory | And 5 more authors.
Acta Materialia | Year: 2013

Crystal defects in a plastically deformed Mg-Zn-Y alloy have been studied on the atomic scale using aberration-corrected scanning transmission electron microscopy, providing important structural data for understanding the material's deformation behavior and strengthening mechanisms. Atomic scale structures of deformation stacking faults resulting from dissociation of different types of dislocations have been characterized experimentally, and modeled. Suzuki segregation of Zn and Y along stacking faults formed through dislocation dissociation during plastic deformation at 300 °C is confirmed experimentally on the atomic level. The stacking fault energy of the Mg-Zn-Y alloy is evaluated to be in the range of 4.0-10.3 mJ m -2. The newly formed nanometer-wide stacking faults with their Zn/Y segregation in Mg grains play an important role in the superior strength of this alloy at elevated temperatures. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


You Z.,CAS Shenyang Institute of Metal Research | Li X.,Brown University | Gui L.,Georgia Institute of Technology | Gui L.,Tsinghua University | And 4 more authors.
Acta Materialia | Year: 2013

Anisotropic plastic deformation in columnar-grained copper in which preferentially oriented nanoscale twins are embedded is studied by experimental testing, crystal plasticity modeling and molecular dynamics simulations. The dominant deformation mechanism can be effectively switched among three dislocation modes, namely dislocation glide in between the twins, dislocation transfer across twin boundaries, and dislocation-mediated boundary migration, by changing the loading orientation with respect to the twin planes. The controllable switching of deformation mechanisms not only leads to a marked dependence of yield strength on loading orientation, but also induces a strong orientation dependence of strain hardening that can be critical for retaining tensile ductility. These results demonstrate a new route for tailoring both nanostructure and loading to control the deformation mechanisms in order to achieve the desired mechanical properties in engineering materials. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Xu D.,CAS Shenyang Institute of Metal Research | Gu T.,Ohio University
International Biodeterioration and Biodegradation | Year: 2014

The study of microbiologically influenced corrosion (MIC) has long been plagued by a lack of clear understanding of MIC mechanisms. In this work, bioenergetics was used to explain why and when sulfate-reducing bacteria (SRB) became aggressive toward carbon steel. Fe2+/Fe0 and acetate+CO2/C3H5O3- (lactate) have similar reduction potentials at pH 7 (-447mV vs.-430mV). Bioenergetically, Fe0 oxidation releases more energy than lactate oxidation, but Fe0 cannot provide organic carbons needed for growth. If there is insufficient carbon source that can diffuse from the bulk fluid to an iron surface, sessile cells at the bottom of an SRB biofilm on the surface may suffer from local carbon source starvation. In this work, mature Desulfovibrio vulgaris (ATCC 7757) biofilms initially grown in ATCC 1249 culture medium on C1018 carbon steel coupons were subjected to starvation by switching to fresh culture media with 0% (control), 90%, 99% and 100% less organic carbon, respectively. It was found that 90% and 99% carbon reductions increased weight loss significantly. Experimental data also showed that 90% carbon reduction caused a 10μm maximum pit depth, largest among all other cases, while 99% carbon reduction yielded the highest specific weight loss of 0.0019g/cm2. © 2014 Elsevier Ltd.


Wang T.,CAS Shenyang Institute of Metal Research | Wang C.,CAS Shenyang Institute of Metal Research | Guo J.,CAS Shenyang Institute of Metal Research | Zhou L.,CAS Shenyang Institute of Metal Research
Materials Science Forum | Year: 2013

A low cost Ni-Fe-based wrought superalloy for 700 °C advance ultra-supercritical coal-fired power plants was developed. The stability of microstructure and mechanical properties of this alloy during long-term thermal exposure was investigated by SEM,TEM and tensile tests. The experimental results showed that the major precipitates in the alloy were spherical γ′, MC and discrete M23C6 distributing along grain boundary after the long-term exposure at 700 and 750 °C and no harmful phases, such as σ phase and η phase, were found. However, after exposure at 800 °C up to 3000 h, small amount of lath-like η phase precipitated at grain boundary by consuming the surrounding γ′. The η phase exhibited a fixed orientation relationship with the γ matrix. During thermal exposure γ′ coarsened with increasing the exposure time and exposure temperature. In addition, all major phases and their stability temperature ranges were calculated by JMatPro and these results were confirmed by the experimental results. The 700 °C tensile tests revealed that the alloy after exposure at 700 and 750 °C for 3000 h exhibited excellent ductility and strength. Therefore, the GH984G alloy possessed excellent stability of microstructure and mechanical properties between 700 and 750 °C up to 3000 h, and it is a promising material for 700 °C advance ultra-supercritical coal-fired power plants. © (2013) Trans Tech Publications, Switzerland.


Huang H.W.,CAS Shenyang Institute of Metal Research | Wang Z.B.,CAS Shenyang Institute of Metal Research | Lu J.,City University of Hong Kong | Lu K.,CAS Shenyang Institute of Metal Research | Lu K.,Nanjing University of Science and Technology
Acta Materialia | Year: 2015

By means of surface mechanical rolling treatment (SMRT), a gradient nanostructured (GNS) surface layer was formed on AISI 316L stainless steel. The mean grain size is ∼30 nm in the topmost surface layer and increases with depth. Tension-compression fatigue measurements were performed on the SMRT sample under the stress-controlled mode. In comparison with the coarse-grained sample, the fatigue strength of the SMRT sample is significantly enhanced in both the low- and high- cycling fatigue regimes. Meanwhile, the fatigue ratio is evidently elevated with an increasing tensile strength in the SMRT sample. The initiation and growth of cracks, the cyclic deformation behaviors, as well as effects of strength and residual stresses, have been investigated to clarify the fatigue mechanism of the SMRT sample. The results emphasized the GNS surface layer enhances the fatigue property by suppressing the initiation of cracks and accommodating a remarkable cyclic plastic strain amplitude. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Chen M.,CAS Shenyang Institute of Metal Research | Shen M.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research | Niu Y.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2012

Dense and well-adherent glass-alumina-NiCrAlY tri-composite coatings were prepared on K38G superalloy substrates at 950 °C. Their thermal shock resistance at 1000 °C was investigated, and compared with two glass-alumina composite coatings. Results indicated that the tri-composite coatings exhibited the best resistance to thermal shock and provided enough protective effect to the substrates from high temperature oxidation. The inclusion of alumina particles and NiCrAlY alloy platelets increased the indentation toughness and thermal expansion coefficient, accounting for the enhancement of thermal shock resistance of the tri-composite coatings. Oxidation of the superalloy substrates, combined with their interaction with glassy coatings, was also discussed. © 2011 Elsevier B.V.


Wang S.Q.,CAS Shenyang Institute of Metal Research
Materials Science Forum | Year: 2013

Atomic structure model of bulk AlCoCrCuFeNi multi-principal-element alloy was build by following the principle of maximum entropy. Morse pair-potentials to describe the inter-atomic interaction among neighboring atoms in the alloy were generated directly from first-principles calculations within density-functional theory. Molecular statics simulation was carried out to achieve the optimized atomic configuration of AlCoCrCuFeNi alloy. The results show that the crystallographic behavior in lattice structure observed experimentally is just caused by the average of the disordered atomic position and composition in wide range since there is neither short-range nor long-range order in the local atomic arrangement of this kind of materials. © (2013) Trans Tech Publications, Switzerland.


Li A.,CAS Shenyang Institute of Metal Research | Li A.,University of Chinese Academy of Sciences | Zhou Y.,CAS Shenyang Institute of Metal Research
Journal of the American Ceramic Society | Year: 2011

Ti3SiC2 joining has been successfully achieved by depositing a thin Cu or Zr layer on it and heat treating at low temperatures of 950° or 1100°C in an argon atmosphere, respectively, which are ∼500°C lower than the previous solid solution joining method. X-ray diffraction and scanning electron microscope analyses reveal that a continuous Cu3Si or Zr-silicide layer forms at the joint interface through the outward diffusion of Si atoms from the Ti3SiC2 substrate into the deposited Cu or Zr layer. The strength of joints is evaluated by tensile bond-strength test and 4-point bending test methods. The Ti 3SiC2/Cu/Ti3SiC2 joints always fail from the substrate instead of from the bonding interface, while the Ti 3SiC2/Zr/Ti3SiC2 joints fail from the joint interface during tensile bond-strength test. The 4-point bending strength of Ti3SiC2/Cu/Ti3SiC2 joints reaches a value of 238 MPa, which is 68% of the Ti3SiC 2 substrate. So joining using a Cu or Zr film as the interlayer followed by heat treating is a practical and efficient method for joining Ti3SiC2. © 2011 The American Ceramic Society.


Shen M.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Chen M.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Journal of the American Ceramic Society | Year: 2011

An aluminosilicate glass coating dispersed with quartz particles was prepared on Ti811 alloy by slurry technique to study its high-temperature performances. The coated and uncoated samples were exposed in air at 1000°C for 50 h, and then characterized using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and microhardness depth profile. Mass gains of the samples with and without coatings were measured during the oxidation. For the samples of Ti811 without the glass coating, thick rutile-TiO2 scales were observed, within which several thin alumina layers presented. Typical oxygen permeation phenomenon was also observed. The mass gains of the samples with the glass coating were measured to be only about 1/10 of those of the samples without coatings, and the oxygen permeation phenomenon was prevented. A Ti5Si3/Ti3Al bilayer was observed beneath the coating, and believed to act as an oxygen diffusion barrier. In general, the quartz particle-reinforced glass coating provided good protection of the alloy Ti811 from high-temperature oxidation and oxygen permeation. © 2011 The American Ceramic Society.


Chen T.,Shandong University | Li X.,Shandong University | Qiu C.,Tsinghua University | Zhu W.,Shandong University | And 5 more authors.
Biosensors and Bioelectronics | Year: 2014

A novel electrochemical sensor for the detection of glucose was constructed based on the use of Co3O4/PbO2 core-shell nanorod arrays as electrocatalysts. In this paper the Co3O4/PbO2 core-shell nanorod arrays grow directly on a flexible carbon cloth substrate by the combination of hydrothermal synthesis and electrochemical deposition methods. The as-prepared hierarchical nanocomposites show the structural characteristics of nanowire core and nanoparticle shell. The carbon cloth-supported Co3O4/PbO2 nanorod array electrode exhibits higher sensitivity (460.3μAmM-1cm-2 in the range from 5μM to 1.2mM) and lower detection limit (0.31μM (S/N=3)) than the carbon cloth-supported Co3O4 nanowire array electrode. Both the three-dimensional network of carbon cloth substrate and the hierarchical nanostructure of binary Co3O4/PbO2 composites make such an electrode have high electrocatalytic activity towards the glucose oxidation. Due to the excellent sensitivity, repeatability and anti-interference ability, the carbon cloth-supported Co3O4/PbO2 nanorod arrays will be the promising materials for fabricating practical non-enzymatic glucose sensors. © 2013 Elsevier B.V.


Singh E.,Rensselaer Polytechnic Institute | Chen Z.,CAS Shenyang Institute of Metal Research | Houshmand F.,Rensselaer Polytechnic Institute | Ren W.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Small | Year: 2013

The static and dynamic wetting properties of a 3D graphene foam network are reported. The foam is synthesized using template-directed chemical vapor deposition and contains pores several hundred micrometers in dimension while the walls of the foam comprise few-layer graphene sheets that are coated with Teflon. Water contact angle measurements reveal that the foam is superhydrophobic with an advancing contact angle of ∼163 degrees while the receding contact angle is ∼143 degrees. The extremely water repellent nature of the foam is also confirmed when impacting water droplets are able to completely rebound from the surface. Such superhydrophobic graphene foams show potential in a variety of applications ranging from anti-sticking and self-cleaning to anti-corrosion and low-friction coatings. A new class of water-repellant graphene foam structure displaying stable superhydrophobic behavior under both static as well as dynamic conditions is presented. The high speed camera image shows a water droplet impacting and successfully rebounding off the graphene foam surface. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang L.,Zhejiang University | Zhang B.,CAS Shenyang Institute of Metal Research | Meng X.,Zhejiang University | Su D.S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
ChemSusChem | Year: 2014

A composite catalyst including palladium nanoparticles on titania (TiO 2) and on nitrogen-modified porous carbon (Pd/TiO2@N=C) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N 2 sorption isotherms show that the catalyst has a high BET surface area (229 m2 g-1) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@N=C catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO 2 (a catalyst for dehydrogenation of formic acid) and Pd/N=C (a catalyst for hydrogenation of vanillin) sites. Triple play: A ternary Pd/TiO2@N=C catalyst is developed by supporting palladium nanoparticles onto a composite support of titania (TiO2) and nitrogen-modified porous carbon. The catalyst is able to fully hydrogenate vanillin, using formic acid, available from biomass, as hydrogen source. Its unique catalytic properties for hydrogenation are due to a synergistic effect between two different types of palladium sites in the catalyst: one for formic acid dehydrogenation and on for vanillin hydrogenation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang Z.,CAS Shenyang Institute of Metal Research | Wang Z.,Case Western Reserve University | Qiu R.L.J.,Case Western Reserve University | Lee C.H.,Case Western Reserve University | And 2 more authors.
ACS Nano | Year: 2013

We report the composition- and gate voltage-induced tuning of transport properties in chemically synthesized Bi2(Te1-xSe x)3 nanoribbons. It is found that increasing Se concentration effectively suppresses the bulk carrier transport and induces semiconducting behavior in the temperature-dependent resistance of Bi 2(Te1-xSex)3 nanoribbons when x is greater than ∼10%. In Bi2(Te1-xSex) 3 nanoribbons with x ≈ 20%, gate voltage enables ambipolar modulation of resistance (or conductance) in samples with thicknesses around or larger than 100 nm, indicating significantly enhanced contribution in transport from the gapless surface states. © 2013 American Chemical Society.


Niu P.,CAS Shenyang Institute of Metal Research | Zhang L.,CAS Shenyang Institute of Metal Research | Liu G.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Advanced Functional Materials | Year: 2012

"Graphitic" (g)-C 3N 4 with a layered structure has the potential of forming graphene-like nanosheets with unusual physicochemical properties due to weak van der Waals forces between layers. Herein is shown that g-C 3N 4 nanosheets with a thickness of around 2 nm can be easily obtained by a simple top-down strategy, namely, thermal oxidation etching of bulk g-C 3N 4 in air. Compared to the bulk g-C 3N 4, the highly anisotropic 2D-nanosheets possess a high specific surface area of 306 m 2 g -1, a larger bandgap (by 0.2 eV), improved electron transport ability along the in-plane direction, and increased lifetime of photoexcited charge carriers because of the quantum confinement effect. As a consequence, the photocatalytic activities of g-C 3N 4 nanosheets have been remarkably improved in terms of •OH radical generation and photocatalytic hydrogen evolution. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Du K.,CAS Shenyang Institute of Metal Research | Guo X.,CAS Shenyang Institute of Metal Research | Guo Q.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research | Tian Y.,Dalian Jiaotong University
Materials Letters | Year: 2013

This work for the first time reports a monolayer plasma electrolytic oxidation (PEO) coating on 2024 Al alloy substrate by transient self-feedback control (TSFC) mode. The monolayer coating without outer porous layer exhibits rather excellent compactness and corrosion protection attributed to extensive distribution of scattered ceramic particles with small size and less porosity. A possible mechanism is proposed to explain the formation of TSFC coating. Due to uniform surface distribution of the filming-formative particles and the discharge energy under high frequency square voltage (HFSV) waveform, the formation of the outer porous layer has been prevented effectively. © 2012 Elsevier B.V. All rights reserved.


Wu Z.-S.,CAS Shenyang Institute of Metal Research | Xue L.,CAS Shenyang Institute of Metal Research | Ren W.,CAS Shenyang Institute of Metal Research | Li F.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Advanced Functional Materials | Year: 2012

Surface modification of carbon materials plays an important role in tailoring carbon surface chemistry to specify their electrochemical performance. Here, a surface modification strategy for graphene is proposed to produce LiF-nanoparticle-modified graphene as a high-rate, large-capacity pre-lithiated electrode for high-power and high-energy lithium ion batteries. The LiF nanoparticles covering the active sites of the graphene surface provide an extra Li source and act as an effective solid electrolyte interphase (SEI) inhibiter to suppress LiFP 6 electrolyte decomposition reactions, affect SEI components, and reduce their thickness. Consequently, the Li-ion diffusion is greatly sped up and the thermodynamic stability of the electrode is significantly improved. This modified graphene electrode shows excellent rate capability and improved first-cycle coulombic efficiency, cycling stability, and ultrahigh power and energy densities accessible during fast charge/discharge processes. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang S.-M.,CAS Shenyang Institute of Metal Research | Jin H.-J.,CAS Shenyang Institute of Metal Research
Applied Physics Letters | Year: 2014

We report a strategy to increase the linear stroke of nanoporous gold (npg) electrochemical actuator, by incorporating solid and parallel gold layers into npg and form Au/npg multilayer composites. The actuation strokes in the direction perpendicular to layer planes are larger than the rule-of-mixture predictions and can be 20% greater than that of monolithic npg; meanwhile, the multilayer composites are stiffer than the npg monolith. Current study provides an approach to simultaneously increase the actuation strain, the effective stiffness, and mechanical stability of actuation material, and thus global performance of np solid actuator. © 2014 AIP Publishing LLC.


Obbard E.G.,CAS Shenyang Institute of Metal Research | Hao Y.L.,CAS Shenyang Institute of Metal Research | Talling R.J.,Imperial College London | Li S.J.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Acta Materialia | Year: 2011

β Phase elasticity, stress-induced α″ transformation and superelasticity in hot-forged Ti-24Nb-4Zr-8Sn-(0.08-0.40)O (wt.%) has been investigated by in situ synchrotron X-ray diffraction, Rietveld refinement and texture analysis. The β elastic constants were determined by Eshelby-Kröner-Kneer self-consistent modelling. A micromechanical model based on texture, martensite crystallography and Schmid law nucleation criteria was used to analyse the generation of non-linear strain. Oxygen increased the C′ cubic shear constant. The β phase showed increased compliance along 〈1 1 0〉β as precursor to transformation, which occurs above 0.15 wt.% O by growth of nanosized nuclei, and is nearly suppressed at 0.40 wt.% O by structural convergence of parent/martensite phases. The shape of the stress-strain curve is due principally to stress-induced martensitic transformation with high-symmetry {7 5 5}β habit planes, and is controlled by oxygen through its effect on the transformation strains and critical shear stress. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Niu P.,CAS Shenyang Institute of Metal Research | Yin L.-C.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,Hefei University of Technology | And 3 more authors.
Advanced Materials | Year: 2014

There is an inherent driving force to narrow the bandgap of photocatalysts towards this value. Introducing heteroatoms as a general strategy of tuning the bandgap of semiconductors has been attempted to narrow the bandgap of melon in order to extend its light absorption range. Compared to the intensive studies on oxygen vacancies, the underlying role of nitrogen vacancies in modulating optical and photocatalytic properties is rarely considered in developing nitride-based photocatalysts. On the other hand, the spatial distribution of dopants is recognized as an essential issue in modifying the electronic structure of photocatalysts. Homogeneous doping of appropriate heteroatoms throughout a whole particle is indispensable for effective bandgap narrowing, while surface doping can only result in some localized states in the bandgap.


Song Y.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research | Shan D.,CAS Shenyang Institute of Metal Research | Yim C.D.,Korea Institute of Materials Science | You B.S.,Korea Institute of Materials Science
Corrosion Science | Year: 2012

The Mg. xZn. y second phases in Mg-5Zn alloy were adjusted by T4 and T6 treatment, and then the role of second phases in the corrosion behavior of Mg-5Zn alloy was investigated. The dimension of the Mg. xZn. y second phases is only some hundred nanometers. They present discrete distribution on the boundaries of the as-received sample and continuous distribution in the T6 sample. The T4 sample in absence of second phases exhibits the best corrosion resistance while the T6 sample with the largest volume fraction of second phases exhibits the worst one, which can be attributed to the micro-cathodic effect of second phases. © 2012 Elsevier Ltd.


Sun Z.,Chinese University of Hong Kong | Sun Z.,CAS Shenyang Institute of Metal Research | Bao Z.,Chinese University of Hong Kong | Fang C.,Chinese University of Hong Kong | Wang J.,Chinese University of Hong Kong
Langmuir | Year: 2012

The formation of different Au nanocrystal core-resin shell structures through the control of the nanocrystal assembly and shell polymerization is investigated. 4-Mercaptophenol is employed together with formaldehyde as the resin monomers. 4-Mercaptophenol molecules bond to the surface of Au nanocrystals so that the resultant phenolic resin can intimately encapsulate Au nanocrystals. The morphologies of the obtained structures are determined by the nanocrystal assembly and the monomer polymerization behaviors, which are controlled by the solution pH as well as the monomer amounts. At pH = 8-9, Au nanorods are assembled and fused together under hydrothermal conditions in a preferential end-to-end manner. The fused structures are coated with a layer of resin, with the thickness controlled by the supplied amounts of the monomers. At pH = ∼10, Au nanorods are coated with resin of controllable thicknesses and separated from each other. The resin-coated Au nanorods are stable in both aqueous and nonaqueous solutions. At pH = ∼12, Au nanorods are coated with a thin layer of resin and assembled together in a side-by-side manner. A similar assembly and resin coating behavior is also observed with Au nanopolyhedrons. Moreover, plasmonic-fluorescent bifunctional structures are readily produced by incorporating CdTe nanocrystals in the resin shell that is coated on Au nanocrystals, owing to the presence of a number of thiol groups in the resin shell. © 2012 American Chemical Society.


Zhang H.,CAS Shenyang Institute of Metal Research | Peng X.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2012

γ-TiAl is attractive for high temperature application, but requires a coating to resist oxidation. In this work, a β-NiAl coating was fabricated on γ-TiAl through a two-step process: electrophoretic deposition (EPD) of particles of Ni and Al and then hot pressing (HP). The β-NiAl coating was insignificantly degraded by interdiffusion with the γ-TiAl substrate and formed an adherent alumina scale by adding a small amount of Y 2O 3 particles during oxidation at 900°C. © 2011 Elsevier B.V.


Luo Z.P.,CAS Shenyang Institute of Metal Research | Mishin O.V.,Technical University of Denmark | Zhang Y.B.,Technical University of Denmark | Zhang H.W.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

Average microstructural parameters and the extent of microstructural heterogeneity in nickel deformed at a high strain rate have been characterized quantitatively and compared to those after compression at a quasi-static strain rate. The microstructure in the high strain rate sample was found to be more refined and less heterogeneous than that in the sample compressed at a low strain rate. The greater refinement in the former sample was achieved due to subdivision by a high frequency of finely spaced low-angle boundaries. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Rong G.,Nanjing University of Science and Technology | Huang D.W.,Shenyang Ligong University | Yang M.C.,CAS Shenyang Institute of Metal Research
Theoretical and Applied Fracture Mechanics | Year: 2012

Ballistic tests are performed by shooting both tungsten fiber/bulk metallic glass W/Zr 58Ti 13Cu 17Ni 12 composite rods (composite rod) and tungsten heavy alloy rods (95W rod) into 30CrMnMo target. The composite rod exhibits self-sharpening behaviors, and its matrix damages and fibers break are limited in a thin, narrow area, which is defined as " edge layer" Penetrating depth of composite rods is 50% deeper than the depth of 95W rods with same dimension size. © 2012 Elsevier Ltd.


Li W.L.,CAS Shenyang Institute of Metal Research | Tao N.R.,CAS Shenyang Institute of Metal Research | Han Z.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Wear | Year: 2012

Dry sliding tribological behaviors of nanocrystalline (NC) and coarse grained (CG) Cu were studied by using a ball-on-plate tribometer with a counterface ball of cemented tungsten carbide. The results showed that prior to oxidation and delamination, the steady-state friction coefficients (FCs) of NC and CG Cu are comparable (∼0.35). As oxidation with delamination of wear surface occur, the FC for either CG or NC Cu increases gradually, approaching a steady-state FC (∼0.63). The wear resistance of the NC Cu was enhanced by at least one order of magnitude under the measured loads ranging from 5. N to 25. N in comparison with the CG counterpart, which is mainly attributed to the higher hardness of the NC layer. © 2011 Elsevier B.V.


Liu C.,CAS Shenyang Institute of Metal Research | Li K.,CAS Shenyang Institute of Metal Research | Shen J.,CAS Shenyang Institute of Metal Research | Zhang J.,CAS Shenyang Institute of Metal Research | Lou L.,CAS Shenyang Institute of Metal Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

The hot-cracking susceptibility of directionally solidified, Ni-based superalloys obtained by different casting technologies, such as high-rate solidification (HRS) and liquid metal cooling (LMC), are compared in this article. Refined microstructures and the improved castability of LMC castings has been found. The improved hot-cracking resistance in castings using the LMC process can be attributed to the decreased length of the uncompensated zone and to the increased grain boundary cohesion in this zone. © The Minerals, Metals & Materials Society and ASM International 2011.


Hao Y.L.,CAS Shenyang Institute of Metal Research | Li S.J.,CAS Shenyang Institute of Metal Research | Prima F.,École Nationale Supérieure de Chimie de Paris | Yang R.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

This paper reports on β-type titanium alloys with high β transus temperature and low martensite start temperature that display high strength and low elastic modulus. The strategy is based on Zr and Sn additions to Ti-Nb-based alloys. The α″ martensite in Ti-24Nb-4Zr-8Sn alloy is structurally much closer to the β phase than other alloys in terms of transformation strain and tetragonality, allowing homogeneously nucleated reversible mechanisms to be triggered before the formation of nanoscaled equiaxed α″ martensite by strain glass transition. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Yao B.,CAS Shenyang Institute of Metal Research | Han Z.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Wear | Year: 2012

Wear of conventional metallic materials involves various complex solid state processes of which the dominant process is elusive. From a thorough experimental investigation on the worn subsurface structure evolution in pure copper specimens with various microstructures, we conclude that the transformation from the subsurface dynamic recrystallization (DRX) structure into the top nanostructured mixing layer (NML) is the most important process which could determine the wear rate. A pronounced correlation is identified that wear rate increases significantly with an increasing grain size or a decreasing hardness of the DRX structure adjacent to the NML. This result points out an effective approach to make materials better against wear by stabilizing the deformed structure against DRX. © 2012 Elsevier B.V.


Zhang Q.K.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

In this study, the in situ tensile creep behaviors of Sn-4Ag/Cu solder joints were observed, and microstructural evolutions of the solder during the deformation processes were characterized by electron backscatter diffraction. The results reveal that slow plastic deformation or grain rotation occurs inside different solder grains, depending on their orientations and distance from the joint interface. When the strain increases to a certain extent, dynamic recovery occurs inside some solder grains, resulting in polygonization and grain subdivision. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Yang L.M.,Hefei University of Technology | Yang L.M.,CAS Shenyang Institute of Metal Research | Zhang Q.K.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

Shear fracture behaviors of Cu/Sn-3Cu/Cu joints with different solder dimensions were investigated. The experimental results demonstrate that, with decreasing ratio R of the solder thickness to length, the interfacial shear strength increased and the fracture mode changed from ductile to a mixture of ductile and brittle. Based on the interfacial stress analysis across the solder joint, a hyperbolic formula expressing the relationship between the interfacial shear strength and the ratio R was proposed. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Su-Hua W.,CAS Shenyang Institute of Metal Research | Bing-zhi D.,CAS Shenyang Institute of Metal Research | Yu H.,CAS Shenyang Institute of Metal Research
Desalination | Year: 2010

Adsorption has been found to be a very popular phenomenon in removing EDCs with membranes. The results show that adsorption ability of bisphenol A (BPA) on membranes is related to the material, which has the best removal rate by polysulphone. The efficiency of an ultrafiltration membrane (PS-20) to remove BPA is examined as a function of solution conditions. Ca2+ doesn't appear to aid retention by "bridging" membrane and BPA molecule or by screening the charge potential of the membrane. However, the retention of BPA is significantly influenced by pH resulting in a drastic decrease in retention when the solution pH exceeds its pKa value. The presence of NOM decreases the adsorption of BPA onto membrane due to its competitive adsorption onto the limited adsorption capability of the membrane. Adsorption onto the PS-20 membrane is driven both by hydrophobic adsorption and hydrogen bonding as physical and chemical interaction respectively. Whereas, the high desorption ratio shows that BPA-polysulphone bonding is not very strong, the ever decreasing retention versus permeate volume reveals that the exact evaluation of removal efficiency of BPA with ultrafiltration is impossible until the saturation is accomplished. © 2009 Elsevier B.V. All rights reserved.


Xue P.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering A | Year: 2012

Low tensile ductility owing to the insufficient strain hardening is the main drawback for ultrafine-grained (UFG) materials, which restricts their practical applications. Here, via a simple friction stir processing technique with additional cooling, we prepared UFG Cu with high strength and tensile ductility. Enhanced strain hardening capacity, which is effective in blocking and accumulating dislocations, was achieved in the present recrystallized UFG microstructure. The enhanced strain hardening capacity is attributed primarily to the low dislocation density, and the presence of large fraction of high angle grain boundaries and a certain amount of coherent twin boundaries. This work provides a strategy for designing UFG materials with good mechanical properties. © 2011 Elsevier B.V.


Tian Y.Z.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

Abundant growth twin boundaries are found and characterized in two bulk eutectic Cu-Ag alloys that can be obtained conveniently. The statistical electron backscattering diffraction results show that both hetero-twin and cube-on-cube orientation relationships coexist in the eutectic Cu-Ag alloy. The tensile strength of the eutectic alloy increases with a decrease in the layer thickness of the Cu/Ag phase. This study provides a potential way to produce bulk eutectic Cu-Ag alloy with abundant twin boundaries that offers a combination of high strength and high ductility. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Xie G.,CAS Shenyang Institute of Metal Research | Lou L.H.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering A | Year: 2012

Creep tests of a directionally solidified (DS) Ni-base superalloy specimens containing local recrystallization (RX) were carried out at 980°C/235. MPa and the influence of the characteristic of RX grain boundary on the formation of creep cracks was investigated. The RX grain boundary morphology, misorientation and dislocation pattern at high, low angle and twin boundaries during creep were examined. It was shown that only a few high angle grain boundaries (GBs), but not all of them cracked during creep and even after ruptured. This is associated with the dislocation mobility at GBs or the morphology of GBs. The possibility of crack formation was discussed based on the transmission behavior of dislocations at different GBs. © 2011 Elsevier B.V.


Mu J.,Northeastern University China | Zhu Z.,CAS Shenyang Institute of Metal Research | Su R.,Beijing Institute of Technology | Wang Y.,Northeastern University China | And 3 more authors.
Acta Materialia | Year: 2013

The deformed-induced microstructure evolution and phase transformation behavior of Ti-based amorphous alloy composites (AACs) containing ductile dendrites in situ formed during solidification were investigated using ex situ transmission electron microscopy (TEM) and in situ high-energy X-ray diffraction (HE-XRD). In situ synchrotron-based HE-XRD experiments provide clear evidence on the deformation-induced phase transformation from β to α″ martensite initiated already in the linear elastic stage of the macroscopic stress-strain curve. Detailed analyses from the diffraction experiments show that the grains that were aligned with [0 0 1]β along the loading direction (LD) were then easily transformed into α″ martensite, whereas the martensitic variants oriented with [1 0 0] α″ along LD were preferentially formed under compression. The current study provides quantitative information about changes in various microstresses between the crystal phase and the amorphous matrix during deformation. Enhancement of the macroscopic plasticity of the AACs was mainly attributed to the strain relaxation in the β phase and to the formation of multiple shear bands in the amorphous matrix triggered by the deformation-induced phase transformation inside β, knowledge of which greatly deepens understanding of the complex micromechanical behaviors in advanced AACs. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Jia P.,Northeastern University China | Liu J.-M.,CAS Shenyang Institute of Metal Research | Wang E.-G.,CAS Shenyang Institute of Metal Research | Han K.,Florida State University
Journal of Alloys and Compounds | Year: 2013

We report that the high magnetic field (HMF) retards crystallization, i.e. helps to keep a fully amorphous state of bulk metallic glass (BMG) upon isothermal annealing in the supercooled liquid region. Particularly, the application of HMF during an annealing process can effectively suppress the crystallization of boride (e.g. Fe23B6-type phase, or even a hard magnetic Fe2B phase) from the amorphous matrix of Fe 71(Nb0.8Zr0.2)6B23 BMG. Thus by delaying crystallization, HMF can enhance the soft magnetic properties of high B content Fe-based bulk amorphous and nanocrystalline materials. © 2013 Elsevier B.V. All rights reserved.


Liu X.,CAS Shenyang Institute of Metal Research | Shan D.,CAS Shenyang Institute of Metal Research | Song Y.,CAS Shenyang Institute of Metal Research | Chen R.,CAS Shenyang Institute of Metal Research | Han E.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2011

The influence of the quantity of the Mg2Sn phase on the corrosion behavior of different solution temperature treated Mg-7Sn magnesium alloy has been investigated by electrochemical measurements, scanning electron microscope (SEM) observation, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. With the increase of solution temperature, the quantity of Mg2Sn phase decreased and the tin concentration of matrix increased. The dissolved tin in Mg matrix took part in the film formation and the constituent of film was magnesium oxide and stannic oxide. The corrosion mode and corrosion rate were associated with the quantity of Mg2Sn phases and tin concentration of the matrix. If most of tin was present as Mg2Sn, the corrosion mode was pitting corrosion and it accelerated the corrosion rate. If most of tin was dissolved in matrix, the corrosion mode was filiform corrosion and it decreased the corrosion rate. The experiment evidences demonstrated that the corrosion resistance can be improved by increasing the tin concentration of matrix and the lowest corrosion rate was observed for sample solution treated at 540 °C. © 2010 Elsevier Ltd.


Xu J.,CAS Shenyang Institute of Metal Research | Ma E.,Johns Hopkins University
Journal of Materials Research | Year: 2014

Bulk metallic glasses (BMGs) exhibit high yield strength but little tensile ductility. For this class of materials, damage tolerance is a key mechanical design parameter needed for their engineering use. Recently we have discovered a correlation between the local structural characteristics in the glass and the propensity for shear transformations. Based on the dependence of glass structure on alloy composition, zirconium (Zr)-rich Zr-titanium (Ti)-copper (Cu)-aluminum (Al) compositions are predicted to be more prone to spread-out plastic deformation and hence profuse shear banding. This structural perspective has guided us to locate a Zr61Ti2Cu25Al12 (ZT1) BMG that exhibits a record-breaking fracture toughness, on par with the palladium (Pd)-based BMG recently developed at Caltech. At the same time, the new BMG consists of common metals and has robust glass-forming ability. Interestingly, the ZT1 BMG derives its high toughness from its high propensity for crack deflection and local loading-mode change (from mode I to substantially mode II) at the crack tip due to extensive shear band interactions. A crack-resistance curve (R-curve) has been obtained following American Society for Testing and Materials (ASTM) standards, employing both single-specimen and multiple-specimen techniques as well as fatigue precracked specimens. The combination of high strength and fracture toughness places ZT1 atop all engineering metallic alloys in the strength-toughness Ashby diagram, pushing the envelop accessible to a structural material in terms of its damage tolerance. Copyright © 2014 Materials Research Society.


Chou T.-C.,National Tsing Hua University | Doong R.-A.,National Tsing Hua University | Hu C.-C.,National Tsing Hua University | Zhang B.,CAS Shenyang Institute of Metal Research | Su D.S.,CAS Shenyang Institute of Metal Research
ChemSusChem | Year: 2014

A promising energy storage material, MnO2/hierarchically porous carbon (HPC) nanocomposites, with exceptional electrochemical performance and ultrahigh energy density was developed for asymmetric supercapacitor applications. The microstructures of MnO2/HPC nanocomposites were characterized by transmission electron microscopy, scanning transmission electron microscopy, and electron dispersive X-ray elemental mapping analysis. The 3-5nm MnO2 nanocrystals at mass loadings of 7.3-10.8wt % are homogeneously distributed onto the HPCs, and the utilization efficiency of MnO2 on specific capacitance can be enhanced to 94-96 %. By combining the ultrahigh utilization efficiency of MnO2 and the conductive and ion-transport advantages of HPCs, MnO2/HPC electrodes can achieve higher specific capacitance values (196F g-1) than those of pure carbon electrodes (60.8F g-1), and maintain their superior rate capability in neutral electrolyte solutions. The asymmetric supercapacitor consisting of a MnO2/HPC cathode and a HPC anode shows an excellent performance with energy and power densities of 15.3Wh kg-1 and 19.8kW kg-1, respectively, at a cell voltage of 2V. Results obtained herein demonstrate the excellence of MnO2/HPC nanocomposites as energy storage material and open an avenue to fabricate the next generation supercapacitors with both high power and energy densities. Shaping up for charge: Hierarchically porous carbons combined with nanosized manganese oxides have been utilized as an asymmetric supercapacitor electrode. The unique hierarchical structures accelerate ion diffusion and increase the active surfaces of manganese oxide nanocrystals. The excellent electrochemical properties of the MnO2/hierarchical porous carbon composites make this material a possible candidate for high energy and power-density supercapacitors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Luo J.,CAS Shenyang Institute of Metal Research | Kang X.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research
ChemPhysChem | Year: 2010

Our previous study found that mechanically milling with magnesium hydride (MgH2) could dramatically improve the dehydrogenation property of ammonia borane (AB). Meanwhile, it appears that the MgH2 additive maintains its phase stability in the milling and subsequent heating process. In an effort to further the mechanistic understanding of the AB/MgH2 system, we reinvestigated the property and structure evolution in the hydrogen release process of the AB/0.5MgH2 sample. Property examination using volumetric method and synchronous thermal analyses showed that the AB/0.5MgH2 sample releases ~13.8 wt% hydrogen after being heated at 3008C. This hydrogen amount is in excess of that available from AB, indicative of the participation of a faction of MgH2 in the dehydrogenation process of AB. Structural and chemical state analyses using Fourier transformation infrared spectroscopy and solid-state 11B nuclear magnetic resonance techniques further showed that part of MgH2 participates in the dehydrogenation process of AB from the first step, resulting in the formation of Mg-B-N-H intermediate species. The incorporation of Mg in AB is believed to be a crucial event leading to dehydrogenation property improvements, particularly for the release of the last equivalent of H2 in AB at relatively moderate temperature. These findings have provided renewed insight into the promoting mechanism of MgH2 on the hydrogen release from AB. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zheng C.,CAS Shenyang Institute of Metal Research | Zheng C.,Max Planck Institute Für Eisenforschung | Raabe D.,Max Planck Institute Für Eisenforschung
Acta Materialia | Year: 2013

The concurrent ferrite recrystallization and austenitic transformation during intercritical annealing of cold-rolled DP steels is investigated by cellular automaton (CA) modeling. The simulations provide insight into the microstructural phenomena that result from the interaction of primary recrystallization and phase transformation. We find that the interaction between ferrite recrystallization and austenite formation affects not only the transformation kinetics but also the morphology and spatial distribution of the austenite. From this we can interpret experimental data of the observed temperature-dependent hardness and its dependence on the two metallurgical processes. The influence of the initial heating rate on subsequent isothermal transformation kinetics and the microstructure evolution is also obtained by the model. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Liu B.,CAS Shenyang Institute of Metal Research | Ren W.,CAS Shenyang Institute of Metal Research | Li S.,CAS Shenyang Institute of Metal Research | Liu C.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Chemical Communications | Year: 2012

Chirality-controlled synthesis of single-walled carbon nanotubes (SWCNTs) is a prerequisite for their practical applications in electronic and optoelectronic devices. We report here a novel bimetallic CoPt catalyst for the selective growth of high quality SWCNTs with a narrow chirality distribution at relatively high temperatures of 800 °C and 850 °C using atmospheric pressure alcohol chemical vapor deposition. The addition of Pt into a Co catalyst forms a CoPt alloy and significantly reduces the diameters of the as-grown SWCNTs and narrows their chirality distributions. This journal is © The Royal Society of Chemistry 2012.


Lu S.D.,CAS Shenyang Institute of Metal Research | Wang Z.B.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering A | Year: 2010

A nanostructured surface layer of about 20 μm in thickness was fabricated on a hot-working tool steel (AISI H13) plate by means of surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated in comparison with its coarse-grained counterpart. Relative to the coarse-grained form, the Cr-diffusion depth was obviously enhanced by SMAT at various chromizing temperatures, with a maximum increment at 600 °C. A duplex chromizing treatment at 600 °C followed by at a higher temperature led to the formation of a much thicker chromized surface layer (up to 30 μm in thickness) on the SMAT sample. This might be attributed to the formation of a large amount of nano-sized chromium compounds in the surface layer at 600 °C, which retarded growth of nano-sized ferrite grains and improved the Cr diffusion at higher temperatures. Gradient distributions of Cr concentration, microstructure and hardness were formed in the chromized surface layer in the SMAT steel after the duplex chromizing treatment, leading to an obvious enhancement in the wear resistance. © 2009 Elsevier B.V. All rights reserved.


Chen C.-M.,Shanxi Institute of Coal CAS Chemistry | Zhang Q.,Tsinghua University | Huang C.-H.,National Tsing Hua University | Zhao X.-C.,CAS Dalian Institute of Chemical Physics | And 6 more authors.
Chemical Communications | Year: 2012

A three-dimensional bubble graphene film, with controllable and uniform macropores and tailorable microstructure, was fabricated by a facile hard templating strategy and exhibit extraordinary electrochemical capacitance with high rate capability (1.0 V s -1). © 2012 The Royal Society of Chemistry.


Du J.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Macromolecular Chemistry and Physics | Year: 2012

Graphene is a potential nanofiller that can dramatically improve the properties of polymer-based composites at a very low loading. This article reviews the state-of-the-art progress in the fabrication, properties, and uses of polymer composites with different kinds of graphene fillers. The results so far reported in the literature indicate that graphene/polymer composites are promising multifunctional materials with significantly improved tensile strength and elastic modulus, electrical and thermal conductivity, etc. Despite some challenges and the fact that carbon naotube/polymer composites are sometimes better in some particular performance, graphene/polymer composites may have wide potential applications due to their outstanding properties and the availability of graphene in a large quantity at low cost. Review: The recent development in the fabrication, properties, applications and fundamental challenges of graphene/polymer composites is reviewed. Graphene/polymer composites are promising multifunctional materials with significantly improved mechanical, electrical, and thermal properties and may have wide potential applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang P.,CAS Shenyang Institute of Metal Research | Zhang Z.J.,CAS Shenyang Institute of Metal Research | Li L.L.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

The fatigue cracking mechanisms at twin boundaries (TBs) are investigated by considering the stacking fault energy, dislocation slip mode and the difference in the Schmid factors (DSF) between matrix and twin. In Cu and its alloys, the occurrence of TB cracking becomes much more frequent with either increasing the alloying component or the DSF. Considering the interactions between dislocations and TBs, a semiquantitative relationship based on the statistical experimental results is established to describe the TB cracking mechanism. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Fu J.W.,CAS Shenyang Institute of Metal Research | Yang Y.S.,CAS Shenyang Institute of Metal Research
Materials Letters | Year: 2013

Phase transformation details in the three-phase region of AISI 304 stainless steel were revealed by quenching. At the initial stage of solidification, microstructure consisting of thin lathy ferrite and austenite forms directly from the melt. When forming lathy ferrite in the two-phase microstructure, Cr concentration at the solid/liquid interface remains almost unchanged and large numbers of Ni solutes are rejected into the liquid. When austenite forms, both Cr and Ni solutes are rejected into the liquid. When this process repeats several times, the concentration of Ni in the liquid becomes higher and Cr solute is slightly enriched. Thus, the retained liquid is transformed into austenite after forming the two-phase microstructure due to high concentration of austenite-stabilizing element. This phase transformation pattern was confirmed by consideration of the difference in Gibbs free energy. © 2012 Elsevier B.V.


Lu K.,CAS Shenyang Institute of Metal Research | Yan F.K.,CAS Shenyang Institute of Metal Research | Wang H.T.,CAS Shenyang Institute of Metal Research | Tao N.R.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

A novel strategy for strengthening austenite steels is introduced by using the unique strengthening effect of nanoscale twins. Austenite grains containing multiple nanoscale twins can be strengthened to a yield strength of a few GPa with very high work-hardening rates. Compared with the conventional dual-phase steels, several austenite steels strengthened by using ultra-strong nanotwinned austenite grains exhibit a superior strength-ductility synergy. Perspectives on future development of the nanotwinned austenite steels and the nanotwin strengthening strategy are presented. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Lu L.,CAS Shenyang Institute of Metal Research | You Z.S.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

Engineering twin boundaries at the nanometer scale is regarded as an effective approach to achieve high strength while maintaining a substantial work-hardening ability. In this paper, the effects of twin thickness, grain size as well as strain rate on the work-hardening behavior of polycrystalline pure Cu with nanoscale twins are analyzed. The contribution of four possible work-hardening components (Types I-IV) to the hardening and softening process of nanotwinned Cu is also discussed. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wang P.,CAS Shenyang Institute of Metal Research
Dalton Transactions | Year: 2012

Ammonia borane (NH 3BH 3, AB) is a unique molecular crystal containing an intriguingly high density of hydrogen. In the past several years, AB has received extensive attention as a promising hydrogen storage medium. Several strategies have been successfully developed for promoting H 2 release and for suppressing the evolution of volatile by-products from the solid-state thermolysis of AB. Several potentially cost-effective and energy-efficient routes for regenerating AB from the spent fuels have been experimentally demonstrated. These remarkable technological advances offer a promising prospect of using AB-based materials as viable H 2 carriers for on-board application. In this perspective, the recent progresses in promoting H 2 release from the solid-state thermolysis of AB and in developing regeneration technologies are briefly reviewed. © 2012 The Royal Society of Chemistry.


Xie G.,CAS Shenyang Institute of Metal Research | Wang L.,CAS Shenyang Institute of Metal Research | Zhang J.,CAS Shenyang Institute of Metal Research | Lou L.H.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2012

The orientational dependence of deformation and recrystallization in an Ni-base single-crystal superalloy indented on the (1 0 0) and (1 1 0) planes was investigated. The surface topography and distribution of slip bands indicated that the deformation depended on the crystallographic orientation. The anisotropy of recrystallization grain growth was observed on the mid-section below the indentation. The size and shape of the recrystallization region showed good correspondence to that of the deformation zone. The orientational dependence of recrystallization was discussed based on the deformation mechanism. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Pei S.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Carbon | Year: 2012

Graphene has attracted great interest for its excellent mechanical, electrical, thermal and optical properties. It can be produced by micro-mechanical exfoliation of highly ordered pyrolytic graphite, epitaxial growth, chemical vapor deposition, and the reduction of graphene oxide (GO). The first three methods can produce graphene with a relatively perfect structure and excellent properties, while in comparison, GO has two important characteristics: (1) it can be produced using inexpensive graphite as raw material by cost-effective chemical methods with a high yield, and (2) it is highly hydrophilic and can form stable aqueous colloids to facilitate the assembly of macroscopic structures by simple and cheap solution processes, both of which are important to the large-scale uses of graphene. A key topic in the research and applications of GO is the reduction, which partly restores the structure and properties of graphene. Different reduction processes result in different properties of reduced GO (rGO), which in turn affect the final performance of materials or devices composed of rGO. In this contribution, we review the state-of-art status of the reduction of GO on both techniques and mechanisms. The development in this field will speed the applications of graphene. © 2011 Elsevier Ltd. All rights reserved.


Zhang D.,CAS Technical Institute of Physics and Chemistry | Zhou C.,CAS Technical Institute of Physics and Chemistry | Sun Z.,CAS Shenyang Institute of Metal Research | Wu L.-Z.,CAS Technical Institute of Physics and Chemistry | And 2 more authors.
Nanoscale | Year: 2012

Recent advances in wet chemical synthesis of magnetically recyclable nanocatalysts (MRNCs), a versatile integration of high catalytic activity and facile recovery, have led to a dramatic expansion of their potential applications. This review focuses on the recent work in the development of metal and metal oxide based MRNCs for catalytic conversion of organic compounds in solution phase. This will be discussed in detail, according to the two main synthesis methods of MRNCs as classified by us. The two methods are: template-assisted synthetic strategy and direct synthetic strategy. And the template-assisted synthesis is further divided into three subcategories, synthetic strategies assisted by hard-, soft-, and mixed hard-soft coupling layers. At the end, we outline future trends and perspectives in these research areas. This journal is © 2012 The Royal Society of Chemistry.


Wu S.,CAS Shenyang Institute of Metal Research | Wen G.,CAS Shenyang Institute of Metal Research | Schlogl R.,Max Planck Institute for Chemistry | Su D.S.,CAS Shenyang Institute of Metal Research
Physical Chemistry Chemical Physics | Year: 2015

Hydrogen peroxide (H2O2) functionalized carbon nanotubes exhibited better catalytic performance than their nitric acid oxidized counterparts in the reduction of nitrobenzene. One important reason may be attributed to the notably less negative oxygenated groups on the surface of the former one. © the Owner Societies 2015.


Xu D.K.,CAS Shenyang Institute of Metal Research | Han E.H.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2013

An investigation of the fatigue behaviour of as-extruded pure Mg demonstrates that the fatigue strength corresponding to 106 cycles is 35 MPa. An analysis of the microstructural evolution during the fatigue process reveals that the activated twins are mainly {101̄2} type and their density increases with the number of fatigue cycles. The twin boundary (TB) cracking due to the interactions between TBs and slip bands is the key reason for the crack initiation of fatigue samples. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Han G.M.,CAS Shenyang Institute of Metal Research | Yu J.J.,CAS Shenyang Institute of Metal Research | Hu Z.Q.,CAS Shenyang Institute of Metal Research | Sun X.F.,CAS Shenyang Institute of Metal Research
Materials Characterization | Year: 2013

The creep property and microstructure evolution of a single crystal superalloy with [011] orientation were investigated at the temperatures of 700 C, 900 C and 1040 C. It is shown that there exist stages of primary, steady-state, and tertiary creep under the lower temperature 700 C. As the temperature increases to high temperatures of 900 C and 1040 C, steady-state creep stage is reduced or disappears and the shape of creep curves is dominated by an extensive tertiary stage. The minimum creep strain rate exhibits power law dependence on the applied stress; the stress exponents at 700 C, 900 C and 1040 C are 28, 13 and 6.5, respectively. Microstructure observation shows that the morphologies of γ′ phase almost keep original shape at the lower temperature 700 C and high applied stress. With the increasing creep temperature, γ′ precipitates tend to link together and form lamellar structure at an angle of 45 inclined to the applied stress. Transmission electron microscopy (TEM) investigations reveal that multiple < 110 > {111} slip systems gliding in the matrix channels and shearing γ′ precipitates by stacking faults or bending dislocation pairs are the main deformation mechanism at the lower temperature of 700 C. At the high temperatures of 900 C and 1040 C, dislocation networks are formed at γ/γ′ interfaces and the γ′ rafts are sheared by dislocation pairs. © 2013 Elsevier Inc.


Pang L.-X.,CAS Shenyang Institute of Metal Research | Wang H.,CAS Shenyang Institute of Metal Research | Zhou D.,CAS Shenyang Institute of Metal Research | Yao X.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2010

A new temperature stable microwave dielectric with low-firing temperature in xBi2MoO6-(1 - x)TiO2 system was prepared by conventional solid state reaction method. The crystalline phases, sintering behavior, microwave dielectric properties of xBi2MoO6-(1 - x)TiO2 ceramics were studied. All the xBi2MoO6-(1 - x)TiO2 ceramics could be well sintered at 850 °C for 3 h. X-ray diffraction analysis showed that tetragonal rutile phase and monoclinic Bi2MoO6 phase coexisted in the ceramic. The permittivity εr changed from 77.5 to 33.5 and the temperature coefficient of resonant frequency τf value shifted from +348.1 to -37.8 ppm/°C as the x value increased from 0.06 to 0.65. The temperature stable microwave dielectric ceramic was obtained when x = 0.57 in the xBi2MoO6-(1 - x)TiO2 system, and it showed excellent dielectric properties of εr = 36.7, Qf = 16,800 GHz and τf = 0 ppm/°C. Crown Copyright © 2010.


Liu C.T.,Qingdao University of Science and Technology | Ma J.,Qingdao University of Science and Technology | Sun X.F.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2010

The oxidation behavior of a single-crystal Ni-base superalloy DD32 was studied in air at 900 and 1000 °C and analyzed by X-ray diffraction (XRD), scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy (SEM/EDS). At 900 and 1000 °C, two oxidation steps appear in the oxidation kinetics. The first one is controlled by NiO growth and the second by Al2O3 growth until a continuous Al2O3 layer formed under the previously grown NiO layer after a critical time. The variations in the chemical composition due to segregations, which resulted from the solidification process, led to the formation of different kinds of oxide scale on the dendritic and interdendritic area during oxidation between 900 and 1000 °C. The scales formed between 900 and 1000 °C were complicated, and consisted of three layers: an outer columnar NiO layer with a small amount of CoO, an intermediate layer mainly composed of W20O58, CrTaO4, a small amount of spinels NiCr2O4, NiAl2O4 and CoAl2O4, an inner continuous layer of α-Al2O3. Crown Copyright © 2009.


Liang Y.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research | Dai H.-B.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2010

By using a modified electroless plating method, a porous Fe-Co-B catalyst is prepared on Ni foam support in order to generate hydrogen from an alkaline sodium borohydride (NaBH4) solution. In this process, hydrogen bubbles originating from electroless deposition function as a dynamic template to form the porous catalyst. The effects of NaBH4, NaOH concentration and reaction temperature on the hydrolysis reaction kinetics are investigated. It has been found that an average hydrogen generation rate of 22 l min-1 g-1 (Fe-Co-B) is achieved in a 15 wt.% NaBH4 and 5 wt.% NaOH solution at 30 °C, and the apparent activation energy of the hydrolysis reaction is determined to be 27 kJ mol-1. The catalyst exhibits a high activity due to its porous structure, which facilitates the access of reactants to the surface active sites of catalyst. © 2009 Elsevier B.V. All rights reserved.


Liu H.,Northeastern University China | Xu Q.,Northeastern University China | Yan C.,CAS Shenyang Institute of Metal Research | Qiao Y.,Northeastern University China
Electrochimica Acta | Year: 2011

The graphite plate is easily suffered from corosion because of CO 2 evolution when it acts as the positive electrode for vanadium redox flow battery. The aim is to obtain the initial potential for gas evolution on a positive graphite electrode in 2 mol dm -3 H 2SO 4 + 2 mol dm -3 VOSO 4 solution. The effects of polarization potential, operating temperature and polarization time on extent of graphite corrosion are investigated by potentiodynamic and potentiostatic techniques. The surface characteristics of graphite electrode before and after corrosion are examined by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The results show that the gas begins to evolve on the graphite electrode when the anodic polarization potential is higher than 1.60 V vs saturated calomel electrode at 20 °C. The CO 2 evolution on the graphite electrode can lead to intergranular corrosion of the graphite when the polarization potential reaches 1.75 V. In addition, the functional groups of COOH and CO introduced on the surface of graphite electrode during corrosion can catalyze the formation of CO 2, therefore, accelerates the corrosion rate of graphite electrode. © 2011 Elsevier Ltd.


Yan M.,CAS Shenyang Institute of Metal Research | Vetter C.A.,North Dakota State University | Gelling V.J.,North Dakota State University
Corrosion Science | Year: 2013

Polypyrrole (PPy) was deposited on Al flakes in the presence of oxyanions (molybdate, phosphate or vanadate) as inhibiting dopants and the PPy modified Al flakes were incorporated into an epoxy primer as protection pigments for AA 2024-T3. The protection performance of the PPy Al flake coating was assessed by electrochemical evaluations including Scanning Vibrating Electrode Technique (SVET), Electrochemical Impedance Spectroscopy (EIS) and salt spray test. The oxyanion doped PPy Al flake coating shows enhanced protection performance for AA 2024-T3. An oxygen scavenger protection mechanism is suggested for PPy in the composite coating, and the roles of Al flake and oxyanions in the formulation are discussed. © 2013 Elsevier Ltd.


Okafor P.C.,CAS Shenyang Institute of Metal Research | Okafor P.C.,University of Calabar | Liu C.B.,CAS Shenyang Institute of Metal Research | Zhu Y.J.,CAS Shenyang Institute of Metal Research | Zheng Y.G.,CAS Shenyang Institute of Metal Research
Industrial and Engineering Chemistry Research | Year: 2011

The corrosion and corrosion inhibition of N80 and P110 carbon steels (CS) in CO2-saturated simulated formation water by rosin amide imidazoline (RAIM) was studied using electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The results indicate that N80 CS performs better than P110 CS with RAIM at lower temperature and P110 CS at higher temperatures. Inhibition efficiency increased with increase in RAIM concentration and temperature. The data suggest that RAIM functioned as inhibitor via a mixed-inhibitor mechanism and the inhibition process is attributed to the formation of a chemically adsorbed film of RAIM on the surface of the metal via its polycentric adsorption sites. Morphological studies of the carbon steel electrode surface were undertaken by scanning electron microscope (SEM) and atomic force microscopy (AFM). © 2011 American Chemical Society.


Sun C.,CAS Shenyang Institute of Metal Research | Xu J.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Industrial and Engineering Chemistry Research | Year: 2011

The effect of sulfate-reducing bacteria (SRB) on corrosion of carbon steels and interaction between SRB and the carbon steel Q 235 are investigated in soil-extract solutions (SES). The results show that corrosion rates are smaller in the SES with SRB during growing period of SRB, but bigger during dying period. The procedures of interactions of SRB and the steel are studied by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA). SRB do not aggregate on the surface of the steel until an anaerobic space is formed. SRB defend themselves against free oxygen by absorbing substances containing nonfree oxygen. © 2011 American Chemical Society.


Dai H.-B.,CAS Shenyang Institute of Metal Research | Liang Y.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research
Catalysis Today | Year: 2011

Calcination treatment is an important step in preparation of supported transition metal catalysts that are effective for promoting the hydrolysis reaction of sodium borohydride. We found that calcination treatment of cobalt-tungsten-boron/nickel foam catalysts results in the appearance of an induction period in their first time use, and the duration of which depends on the calcination temperature and atmosphere. Upon reusing the catalysts, the induction period completely disappeared. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and synchronous thermal analyses techniques were employed to study the mechanism underlying the induction period phenomenon. Our study results showed that the appearance/disappearance of the induction period should be correlated with the desorption/reabsorption of hydrogen in the catalysts. © 2010 Elsevier B.V.


Li W.,CAS Shenyang Institute of Metal Research | Liu J.,CAS Shenyang Institute of Metal Research | Yan C.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2011

A graphite/graphite oxide (GO) composite electrode for vanadium redox battery (VRB) was prepared successfully in this paper. The materials were characterized with X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The specific surface area was measured by the Brunauer-Emmett-Teller method. The redox reactions of [VO2] +/[VO]2+ and V3+/V2+ were studied with cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the electrochemical performances of the electrode were improved greatly when 3 wt% GO was added into graphite electrode. The redox peak currents of [VO2]+/[VO]2+ and V3+/V 2+ couples on the composite electrode were increased nearly twice as large as that on the graphite electrode, and the charge transfer resistances of the redox pairs on the composite electrode are also reduced. The enhanced electrochemical activity could be ascribed to the presence of plentiful oxygen functional groups on the basal planes and sheet edges of the GO and large specific surface areas introduced by the GO. © 2011 Elsevier Ltd. All rights reserved.


Wang H.,Joseph Fourier University | Wang H.,CAS Shenyang Institute of Metal Research | Rodney D.,Joseph Fourier University | Xu D.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The atomic-scale process of vacancy clustering, of fundamental importance in conditions of quenching, irradiation, and plastic deformation, is studied in aluminum. Clustering is known to lead to large crystalline defects such as dislocation loops, but the early stages of the process are still largely unknown. Using a combination of molecular dynamics simulations, the activation-relaxation technique and kinetic Monte Carlo simulations, a specific cluster, containing five vacancies and forming a local body-centered-cubic cell in the face-centered-cubic lattice, is found to play a crucial role. It is revealed that this cluster of very high stability is the nucleus for the growth of larger clusters during annealing of quenched supersaturated samples. © 2011 American Physical Society.


Chen X.-Q.,CAS Shenyang Institute of Metal Research | Niu H.,CAS Shenyang Institute of Metal Research | Franchini C.,CAS Shenyang Institute of Metal Research | Franchini C.,University of Vienna | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We reconsider and interpret the mechanical properties of the recently proposed allotrope of carbon, T-carbon, using density functional theory in combination with different empirical hardness models. In contrast with the early estimation based on Gao 's model, which attributes to T-carbon a high Vickers hardness of 61 GPa comparable to that of superhard cubic boron nitride (c-BN), we find that T-carbon is not a superhard material, since its Vickers hardness does not exceed 10 GPa. Besides providing clear evidence for the absence of superhardness in T-carbon, we discuss the physical reasons behind the failure of Gao 's and Simunek and Vackár's (SV) models in predicting the hardness of T-carbon, residing in their improper treatment of the highly anisotropic distribution of quasi-sp3-like C-C hybrids. A possible remedy for the Gao and SV models based on the concept of the superatom is suggested, which indeed yields a Vickers hardness of about 8 GPa. © 2011 American Physical Society.


Chen Y.,CAS Shenyang Institute of Metal Research | Hu Q.-M.,CAS Shenyang Institute of Metal Research | Yang R.,CAS Shenyang Institute of Metal Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The structural phase transitions of yttrium under high pressure up to 300 GPa have been studied by using the first-principles, pseudopotential plane-wave method based on density functional theory. The experimental rare-earth structure sequence with increasing pressure is successfully reproduced. The yet unknown distorted face-centered cubic (dfcc) phase is determined to be of the R3̄m space group. In addition, the P6222 phase is predicted to be energetically more stable beyond the pressure range for dfcc. Accurate phonon-dispersion calculations demonstrate that the P6222 phase is dynamically stable beyond pressure of about 206 GPa. The corresponding projected band structures, density of states, and charge density differences are given in order to clarify the electronic origins of the stability of the P6 222 phase under pressure. © 2011 American Physical Society.


Rinaldi A.,Fritz Haber Institute | Tessonnier J.-P.,Fritz Haber Institute | Schuster M.E.,Fritz Haber Institute | Blume R.,Fritz Haber Institute | And 7 more authors.
Angewandte Chemie - International Edition | Year: 2011

Sneaked in: Carbon atoms from defective supports are incorporated in nickel nanoparticles at relatively low temperatures (for example in a Ni(100) surface; Ni-brown, C-black) The dissolved carbon not only modifies the electronic properties of the metal but it also leads to a reconstruction of the nanoparticles. These findings may explain many of the differences in catalytic activity observed when supporting metals on carbon. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu C.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Materials Today | Year: 2013

Notable progress has been made on the synthesis, properties and uses of carbon nanotubes (CNTs) in the past two decades. However, the controlled growth of single-wall CNTs (SWCNTs) with predefined and uniform structures remains a big challenge, and making full use of CNTs in applications still requires great effort. In this article, our strategies and recent progress on the controlled synthesis of SWCNTs by chemical vapor deposition are reviewed, and the applications of CNTs in lithium-ion batteries, transparent conductive films, and as connectors of metal atomic chains are discussed. Finally, future prospects for CNTs are considered.


Wang Y.-X.,CAS Shenyang Institute of Metal Research | Fu J.-W.,CAS Shenyang Institute of Metal Research | Yang Y.-S.,CAS Shenyang Institute of Metal Research
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

The influence of Nd addition on the microstructures and mechanical properties of AZ80 magnesium alloys was investigated. The results show that the microstructure of as-cast AZ80 magnesium alloy is modified effectively with the addition of 1.0 Nd, the grain size is decreased from 448 to 125 μm, new rod-shaped Al 11Nd 3 phase and block-shaped Al 2Nd phase are observed in the as-cast microstructure, and β-Mg 17Al 12 phases are refined and become discontinuous. The addition of Nd suppresses the discontinuous precipitations at grain boundaries during aging, and the time of reaching the peak hardness is delayed. With the addition of 1.0 Nd, the combined properties reach an optimum, the yield strength, tensile strength and elongation are 103.7 MPa, 224.0 MPa and 8.4, respectively. After T6 heat treatment, the yield strength and tensile strength of the AZ80-1.0Nd alloy are increased to 141.1 and 231.1 MPa, respectively. © 2012 The Nonferrous Metals Society of China.


Wang H.,CAS Shenyang Institute of Metal Research | Xu D.S.,CAS Shenyang Institute of Metal Research | Yang R.,CAS Shenyang Institute of Metal Research
Philosophical Magazine Letters | Year: 2014

Dislocation-grain boundary interaction is considered as the core issue of fatigue crack initiation in α-titanium alloys, where, however, the underlying processes still remain unclear. In the present study, the interaction between 〈a〉-dislocations and coherent twin boundaries is simulated with molecular dynamics under various tensile loading orientations. Plastic deformation is found to depend on the tensile orientation, and two typical processes are revealed. In the first, the dislocation transfers into the neighbour grain across the boundary, promoting deformation twinning followed by basal crack initiation, while in the second, the dislocation rebounded at the boundary, resulting in basal crack nucleation therein. In both cases, residual defect structures are left at the boundaries. These results indicate that there exist a wide range of loading orientations, under which dislocation-coherent twin boundary interaction promotes crack initiation on the basal plane; hence, implying its potential relevance to fracture faceting in α-titanium alloys. © 2014 © 2014 Taylor & Francis.


Peng X.,CAS Shenyang Institute of Metal Research | Guan Y.,CAS Shenyang Institute of Metal Research | Dong Z.,CAS Shenyang Institute of Metal Research | Xu C.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2011

The dispersion of CeO2 nanoparticles resulted in a decrease of the oxidation rate of an ultrafine-grained Ni2Al3 at 1000°C. The reason is explained as follows. During oxidation many Ce ions are released from the CeO2 nanoparticles that are enveloped by the inward growing α-Al2O3 from the scale/metal interface due to an increased solubility. The Ce ions transport outward along grain boundaries of the scale, retarding the diffusion of Al ions for the thickening of the outer θ-Al2O3. This explanation is consistent with an observation that many CeO2 nano-precipitates appeared mainly in the near-surface zone of the formed alumina scale. © 2011 Elsevier Ltd.


Shao X.H.,CAS Shenyang Institute of Metal Research | Yang Z.Q.,CAS Shenyang Institute of Metal Research | Ma X.L.,CAS Shenyang Institute of Metal Research
Philosophical Magazine Letters | Year: 2014

Basal stacking faults (SFs) enriched with Zn/Y are identified in an Mg 97Zn1Y2 alloy, and the interaction between SFs and {101̄2} deformation twins (DTs) is characterized at the atomic scale by means of high-resolution transmission electron microscopy. Such an interaction results in deviations of twin angle from its theoretical value and twin boundary (TB) from its (101̄2) habit plane. In addition, the DT-SF reaction not only leads to the TB with terraces along basal planes, but also makes the TB broaden with severe distortion. The role of long-period stacking ordered lamellae in propagation of DTs is also clarified based on the atomic-scale high-resolution images. © 2014 Taylor & Francis.


Du X.-M.,Shenyang Ligong University | Wu E.-D.,CAS Shenyang Institute of Metal Research
Materials Science Forum | Year: 2011

Grand Canonical Monte Carlo (GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on crossing the critical temperature in all-silica ZSM-5 zeolite in this paper. The results indicated that the adsorbed amounts of hydrogen increased with decreasing temperatures and increasing pressures. The highest hydrogen uptake value is 2.24 wt% at 25 K and 10000 kPa. By comparing the variation of the hydrogen adsorption isotherms on crossing the critical temperature, it is shown that the micropore filling and capillary condensation were the main adsorption mechanism under the critical temperature of hydrogen, and the micropore filling was the adsorption mechanism above the critical temperature. The results and data of hydrogen adsorption properties obtained from the simulations are theoretically significant for understanding of the mechanism of hydrogen storage on microporous zeolites. © (2011) Trans Tech Publications.


Yu R.,Tsinghua University | Zhu J.,Tsinghua University | Ye H.Q.,CAS Shenyang Institute of Metal Research
Computer Physics Communications | Year: 2010

We present an efficient method to obtain single-crystal elastic constants. Using the method, the computation effort for the complete set of elastic constants (21 components for a triclinic crystal) of a crystal under a given strain state is similar to that for the bulk modulus, where the latter is normally calculated first together with the equilibrium volume by fitting the volume-dependent energy to an equation of state. The idea in the efficiency improvement is to apply linear-independent coupling strains to a crystal, and to extract the complete set of elastic constants simultaneously. For the new method, a single set of strains are universally applicable to all crystals, and less number of strains are needed for crystals of higher symmetry. Calculated single-crystal elastic constants of cubic diamond, hexagonal osmium, orthorhombic TiSi2 and monoclinic Mg5Si6 are given as examples. © 2009 Elsevier B.V. All rights reserved.


Tegner B.E.,University of Edinburgh | Zhu L.,University of Edinburgh | Zhu L.,CAS Shenyang Institute of Metal Research | Ackland G.J.,University of Edinburgh
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Titanium alloys exhibit three distinct crystal structures: α, β, and ω. For various applications alloying elements can be used to stabilize the desired phase. Extensive data exist to determine the thermodynamic equilibrium phase, typically phase coexistence. However, the normal state of commercial alloys is a quenched solid solution. While alloy designers have well-established rules of thumb, rigorous theory for nonequilibrium single-phase crystal stability is less well established. We develop a theory to predict which phase a particular alloy will adopt, as a function of minor element concentration. We use two different methods based on density functional theory with pseudopotentials and plane waves, with either explicit atoms or the virtual crystal approximation (VCA). The former is highly reliable, while the latter makes a number of drastic assumptions that typically lead to poor results. Surprisingly, the agreement between the methods is good, showing that the approximations in the VCA are not important in determining the phase stability and elastic properties. This allows us to generalize, showing that the single-phase stability can be related linearly to the number of d electrons, independent of the actual alloying elements or details of their atomistic-level arrangement. This leads to a quantitative measure of β stabilization for each alloying transition metal. © 2012 American Physical Society.


He J.,University of Vienna | Chen M.-X.,University of Vienna | Chen X.-Q.,CAS Shenyang Institute of Metal Research | Franchini C.,University of Vienna | Franchini C.,CAS Shenyang Institute of Metal Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

By means of hybrid density functional theory we investigate the evolution of the structural, electronic, and magnetic properties of the colossal magnetoresistance (CMR) parent compound LaMnO 3 under pressure. We predict a transition from a low-pressure antiferromagnetic (AFM) insulator to a high-pressure ferromagnetic (FM) transport half metal (tHM), characterized by a large spin polarization (≈80-90%). The FM-tHM transition is associated with a progressive quenching of the cooperative Jahn-Teller (JT) distortions which transform the Pnma orthorhombic phase into a perfect cubic one (through a mixed phase in which JT-distorted and regular MnO 6 octahedra coexist), and with a high-spin (S=2, m Mn=3.7μ B) to low-spin (S=1, m Mn=1.7μ B) magnetic moment collapse. These results interpret the progression of the experimentally observed non-Mott metalization process and open up the possibility of realizing CMR behaviors in a stoichiometric manganite. © 2012 American Physical Society.


Niu H.,CAS Shenyang Institute of Metal Research | Wang J.,CAS Shenyang Institute of Metal Research | Chen X.-Q.,CAS Shenyang Institute of Metal Research | Li D.,CAS Shenyang Institute of Metal Research | And 5 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

By electron and x-ray diffraction we establish that the CrB 4 compound discovered over 40 years ago crystallizes in the oP10 (Pnnm) structure, in disagreement with previous experiments but in agreement with a recent first-principles prediction. The 3D boron network in this structure is a distorted version of the rigid carbon sp3 network proposed recently for the high-pressure C 4 allotrope. Our systematic density functional theory analysis of the electronic, structural, and elastic properties in ten related transition metal TMB 4 tetraborides (TM = Ti, V, Cr, Mn, Fe and Y, Zr, Nb, Mo, Tc) identifies CrB 4 as the prime candidate to be a superhard material. In particular, the compound's calculated weakest shear and tensile stresses exceed 50 GPa, and its Vickers hardness is estimated to be 48 GPa. We compare the reported and estimated Vickers hardness for notable (super)hard materials and find that the CrB 4 calculated value is exceptionally high for a material synthesizable under standard ambient-pressure conditions. © 2012 American Physical Society.


Ni D.R.,CAS Shenyang Institute of Metal Research | Chen D.L.,Ryerson University | Xiao B.L.,CAS Shenyang Institute of Metal Research | Wang D.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
International Journal of Fatigue | Year: 2013

3 mm thick rolled SiCp/AA2009 sheet in T351 condition was subjected to friction stir welding (FSW). FSW generated high residual stresses with the peak value occurring in the weld center. While the FSW joint showed a shorter fatigue life than the base material (BM) at stress amplitudes higher than 150 MPa, it had a fatigue life equivalent to the BM at lower stress amplitudes with a fatigue limit of about 100 MPa. In the BM the fatigue crack initiated at the SiCp agglomeration or inclusions; however, in the joint the initiation zone was mainly characterized by the formation of dimples. © 2013 Elsevier Ltd. All rights reserved.


Lai Q.Q.,CAS Shenyang Institute of Metal Research | Zhang L.,CAS Shenyang Institute of Metal Research | Eustathopoulos N.,Grenoble Institute of Technology
Acta Materialia | Year: 2013

The wetting of Cu-Fe two-phase composites by molten Sn is studied by the sessile drop technique under high vacuum at 400 C. In this system Sn reacts with both solid components, forming intermetallic compounds. It is found that the curve of contact angle vs. the surface fraction of components passes through a minimum, behaviour that cannot be interpreted by existing models describing wetting of heterogeneous surfaces and/or reactive wetting. It is shown that the observed enhanced wetting can be explained by the dissolution contrast of Cu and Fe phases, leading to interfacial microroughness, thus providing an additional driving force for wetting. In order to take into account this new effect of interfacial reactions on wettability, an equation similar to Wenzel's equation is established. It is shown that this equation can explain the change in wettability of composites when Sn is replaced by SnPb eutectic presenting a lower reactivity than pure Sn, as well as the effect on wettability observed when the scale of composite microstructure is changed with the surface fraction of components remaining constant. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wang J.,CAS Shenyang Institute of Metal Research | Wang Z.Y.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Materials Chemistry and Physics | Year: 2013

The corrosion evolution of weathering steel in Qinghai salt lake atmospheres as a function of exposure duration (up to 30 months) was investigated by corrosion weight gain, XRD, SEM, EDX and electrochemical techniques. The results indicated that the corrosion kinetics was closely related to the characteristics of the rust layer including composition, structure and electrochemical properties. The weight loss monotonically increased as exposure time prolonged with the fluctuations of average corrosion rate. The rust composition was mainly changed from γ-FeOOH and β-FeOOH (6 months), via β-FeOOH and magnetite (18 months), to magnesioferrite and iowaite (30 months). Correspondingly, the rust structure altered from loose and porous (6 months), via relative dense and adherent (18 months), to incompact and discontinuous again (30 months). The result of electrochemical measurements showed that rust resistance was very small, indicating that the rust layer had a poor barrier function which cannot prohibit the corrosion of steel effectively. The presence of iowaite (Mg 4Fe(OH)8OCl·4H2O), which could attract Cl ions due to its special structure, was detrimental to the corrosion resistance of the rust layer and responsible for the poor weatherability of weathering steel. © 2013 Elsevier B.V. All rights reserved.


Chen S.,CAS Shenyang Institute of Metal Research | Zhao M.,CAS Shenyang Institute of Metal Research | Rong L.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering A | Year: 2013

The hydrogen-induced cracking behavior is investigated in two Fe-Ni based austenitic alloys with different amounts of γ' phase. It is observed that intergranular cracking existed in both alloys, while hydrogen-induced twin boundary cracking only occurred in the alloy with higher amount of γ' phase. The occurrence of twin boundary cracking is primarily related to the stacking fault energy (SFE) of alloys, which decreases with the increasing amounts of γ' phase. Enhanced slip planarity and increased difficulty in cutting through twin boundary are observed in the low-SFE alloy. Therefore, twin boundary cracking is induced by cooperative effects of SFE and hydrogen in Fe-Ni based austenitic alloys. © 2012 Elsevier B.V.


Yang J.,CAS Shenyang Institute of Metal Research | Xu J.,CAS Shenyang Institute of Metal Research | Zhang G.-P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2013

The mechanical behavior of small-sized Ti alloy containing only a few colonies is expected to be different from that of its bulk counterpart. Here, we found that depending on the relation between the geometrical and colony scales of the small-sized Ti alloy, fracture did not always occur preferentially in the colony with the maximum Schmid factor. The proposed model suggests that the local strain level in the colony is a dominant factor. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Zhang Z.J.,CAS Shenyang Institute of Metal Research | An X.H.,CAS Shenyang Institute of Metal Research | Zhang P.,CAS Shenyang Institute of Metal Research | Yang M.X.,Control Iron and Steel Research Institute, China | And 3 more authors.
Scripta Materialia | Year: 2013

As the slip mode plays an important role in dislocation evolution and mechanical behavior, the effects of the slip mode on the high-cycle fatigue behaviors of ultrafine-grained (UFG) Cu and Cu-Zn alloys were evaluated. It is found that the fatigue limits can be improved largely by changing the slip mode to hinder dynamic recovery and recrystallization through the addition of Zn in comparison with UFG Cu with wavy-slip mode because of the serious strain localization and microstructural instability of the latter.© 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Pan Q.S.,CAS Shenyang Institute of Metal Research | Lu Q.H.,CAS Shenyang Institute of Metal Research | Lu L.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2013

Polycrystalline columnar-grained bulk Cu samples containing preferentially oriented nanoscale twins have been synthesized by means of direct current electrodeposition. The S-N curves under tension-tension fatigue tests suggested that the fatigue limit (σmax = 162 MPa at 107) of nanotwin Cu is greatly improved over that of the coarse-grained Cu with essentially a similar grain size (σmax = 110 MPa at 10 7). It is found that the majority of twin boundaries are quite stable during cyclic deformation. Distinct "zigzag" slip bands acrossing a few twin planes are prevalently observed in the grain interiors. Schmid factor analysis shows that the "zigzag" slip bands result from one primary slip system activation of threading dislocations propagation within the twin lamellae, which is fundamentally different from that of polycrystal materials. The nanoscale twin confinement of activated threading dislocations suppresses the stress concentration, retards fatigue crack initiation and enhances the fatigue limit. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Hu Q.-M.,CAS Shenyang Institute of Metal Research | Yang R.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2013

Stacking fault energy (SFE) plays an important role in the plastic deformation of metals. As compared to those of face-centered cubic metals, the SFEs of hexagonal close-packed (hcp) metals are less reported in literature. In this paper, we derive the expressions of four types (I1, I 2, E and T2) of basal plane SFEs of hcp metals in terms of the interlayer interaction energies within the framework of the Ising model. The SFEs of 14 kinds of hcp metals are then evaluated with the interlayer interaction energies extracted from the total energies of four prototypes calculated by using the first-principles full-potential augmented plane-wave method. We show that the hcp metals can be divided into three types according to their interlayer interaction energies. For all the hcp metals involved in this study, I1 has the lowest SFE, whereas E has the highest. The metals (Mg, Co, Zn and Cd) with principal slip system (0 0 0 1)[112̄0] generally have low basal plane SFEs. The I1 and T2 SFEs increase linearly with the energy difference between double hexagonal close-packed and hcp structures, whereas the I2 and E SFEs increase linearly with the energy difference between the short-period twin and hcp structures, indicating a trivial contribution of the interaction energy between atomic layers over third nearest neighbors to the SFEs. The SFEs also correlate with the cohesive energy density (cohesive energy of unit volume) with the exception of Be, Co, Tc and Re. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Sheng N.C.,CAS Shenyang Institute of Metal Research | Liu J.D.,CAS Shenyang Institute of Metal Research | Jin T.,CAS Shenyang Institute of Metal Research | Sun X.F.,CAS Shenyang Institute of Metal Research | Hu Z.Q.,CAS Shenyang Institute of Metal Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

The microstructural evolution and bonding behavior of transient liquid phase (TLP) bonded joints for single-crystal superalloy samples with a 300-μm-wide gap have been investigated. The results show that at the initial stage, the interface grows with a cellular structure. With the increase of time, the length and numbers of the cellular structures decrease. At the final stage, the interface evolves with a planar manner. The gradient of B ahead of the liquid/solid interface exists and becomes sharper from the initial to the final analyzed from the electron probe microanalysis (EPMA) results. Inevitably, isolated grain forms during the evolution of the interface and the growth rate of isothermal solidification zone (ISZ) changes through the whole bonding process, and these both deviate from the traditional TLP bonding models. The mechanisms of the formation of the isolated grain boundaries and the reasons for the deviation of the solidification rate are discussed. Also, some effective methods to avoid the formation of isolated grain boundaries in the ISZ are proposed. © 2012 The Minerals, Metals & Materials Society and ASM International.


Chen J.C.,CAS Shenyang Institute of Metal Research | Zhang Y.,Tsinghua University
Journal of Materials Science and Technology | Year: 2013

Densification behaviors of SrO-BaO-Nb2O5-SiO2 based glass-ceramics prepared by conventional sintering were investigated with an emphasis on the influence of P2O5 content. Although P2O5 dopant did not modify the surface crystallization mechanism, it resulted in a decrease of the glass transition temperature, which facilitates the viscous glass flow necessary for sintering. However, premature crystallization of (Sr,Ba)Nb2O6 induced by addition of excess amount of P2O5 essentially retarded sintering due to the formation of closed pores in the matrix. The SrO-BaO-Nb2O5-SiO2 glass with 1.0 mol% P2O5 (SBN-1P) showed the best sinter densification, which was accomplished at about 850°C. © 2013.


Zhang T.J.,Chongqing University | Zhang T.J.,CAS Shenyang Institute of Metal Research
Advanced Materials Research | Year: 2013

It is very important to produce 55Q steel with the exact carbon content. Low and inconsistent carbon elemental recovery problems are often encountered when adding pig iron, or carbon powder into the baths of light rail steel. This is the case because carbon presents some of the following characteristics: lower density much more than the molten steel, low solubility in the liquid steel, high affinity due to oxygen. These circumstances lead to difficulties or risks, such as: poor or erratic recovery of alloying carbon element, violent and dangerous splashing, adverse environmental impact. To counter these problems existed in conventional method, carbon cored wire was prepared and wire injection process introduced in this work, and the effects of parameters such as feeding rate, etc on carbon recovery are investigated. The results show when using the carbon wire injection method, stable carbon addition is obtained, that is, the mean recovery of the carbon absorption is 90%, and what's more, the carbon content is under control accurately and environment improved. © (2013) Trans Tech Publications, Switzerland.


Xu X.,Tongji University | Liu G.,CAS Shenyang Institute of Metal Research | Azad A.K.,University of Brunei Darussalam
International Journal of Hydrogen Energy | Year: 2015

Constituting plasmonic-metal nanostructures is an efficient way in the design and development of active photocatalytic systems. Here we demonstrate a simple one-step reduction process that can in situ grow plasmonic silver nanoparticles on the surface of AgTaO3. The exsolution of silver out of AgTaO3 does not seem to have a significant impact on the crystal integrity, whilst its visible light sensitivity is greatly enhanced. Such Ag nanoparticles decorated AgTaO3 system showed improved photocatalytic hydrogen evolution both under visible and full range irradiation. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Liu G.,CAS Shenyang Institute of Metal Research | Yin L.-C.,CAS Shenyang Institute of Metal Research | Wang J.,CAS Shanghai Institute of Applied Physics | Niu P.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Energy and Environmental Science | Year: 2012

Narrowing the bandgap of wide-bandgap semiconductor photocatalysts (for instance, anatase TiO 2) by introducing suitable heteroatoms has been actively pursued for increasing solar absorption, but usually suffers from a limited thermodynamic/kinetic solubility of substitutional dopants in bulk and/or dopant-induced recombination centres. Here we report a red anatase TiO 2 microsphere with a bandgap gradient varying from 1.94 eV on its surface to 3.22 eV in its core by a conceptually different doping approach for harvesting the full spectrum of visible light. This approach uses a pre-doped interstitial boron gradient to weaken nearby Ti-O bonds for the easy substitution of oxygen by nitrogen, and consequently it substantially improves the nitrogen solubility. Furthermore, no nitrogen-related Ti 3+ was formed in the red TiO 2 due to a charge compensation effect by boron, which inevitably occurs in common nitrogen doped TiO 2. The red anatase TiO 2 exhibits photoelectrochemical water splitting activity under visible light irradiation. The results obtained may shed light on how to increase high visible light absorbance of wide-bandgap photocatalysts. © 2012 The Royal Society of Chemistry.


Yang Q.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Zhang Q.,CAS Shenyang Institute of Metal Research | Zheng M.Y.,Harbin Institute of Technology | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2013

Friction stir processing (FSP) was applied to Mg-Gd-Y-Zn-Zr casting, producing a fine-grained structure of ∼3 μm with a long-period stacking ordered phase distributed within the grains and predominantly high-angle grain boundaries. This FSP alloy exhibited superior high-strain-rate superplasticity at 350-500°C. A maximum superplasticity of 3570% was achieved at 425°C and a strain rate of 3 × 10-2 s-1. Such superior superplasticity is attributed to the thermally stable microstructure and good deformation compatibility. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Zhou G.,CAS Shenyang Institute of Metal Research | Wang D.-W.,University of Queensland | Li F.,CAS Shenyang Institute of Metal Research | Hou P.-X.,CAS Shenyang Institute of Metal Research | And 5 more authors.
Energy and Environmental Science | Year: 2012

We report the template-directed synthesis of sulphur-carbon nanotubes and their use to form a membrane that is binder-free, highly conductive and flexible. This nanostructured membrane is used as a self-supporting cathode without metal current-collectors for Li-S batteries. The membrane cathode has a high electrical conductivity and renders a long life of sulphur of over 100 charge-discharge cycles. High discharge capacity of sulphur was attained at 712 mA h gsulphur -1 (23 wt% S) and 520 mA h g sulphur -1 (50 wt% S) at a high current density (6 A g sulphur -1). The overall capacity of the flexible cathode correspondingly reaches 163 mA h g-1 (23 wt% S) and 260 mA h g -1 (50 wt% S). These results demonstrate the great potential of this nanostructured flexible membrane as a cathode for Li-S batteries with fast charge-discharge performance and long life. © 2012 The Royal Society of Chemistry.


Wu T.-T.,CAS Shenyang Institute of Metal Research | Xie Y.-P.,CAS Shenyang Institute of Metal Research | Yin L.-C.,CAS Shenyang Institute of Metal Research | Liu G.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Journal of Physical Chemistry C | Year: 2015

Revealing the key factors of controlling the reduction and oxidation half reactions of photocatalysis is necessary in order to obtain the implications for designing and developing efficient photocatalysts. In this work, boron-doped TiO2 microspheres consisting of rutile nanorods with the top reactive {111} facets were synthesized by the acidic hydrolysis of TiB2. The thermal diffusion of boron from the inner to surface part of the microspheres results in switching of the preference from photocatalytic H2 evolution to O2 evolution. This switching is caused by the downward shift of surface band edges with the incorporation of boron in surface. © 2014 American Chemical Society.


Xiong L.,CAS Shenyang Institute of Metal Research | Liu S.,CAS Shenyang Institute of Metal Research | Rong L.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2010

A porous nickel support was successfully prepared by uniaxial compression of nickel powders. Microstructures and mechanical properties of Nb40Ti30Ni30 membranes fabricated by magnetron sputtering were investigated. Deposited and annealed Nb40Ti30Ni30 membranes consisted of amorphous and crystalline phases, respectively. Higher base temperature was shown to increase the hardness and elastic modulus of the Nb40Ti30Ni30 membrane. Pd/Nb40Ti30Ni30/Pd/porous nickel support composite membranes were then fabricated using a multilayer magnetron sputtering method. The hydrogen permeability of the composite membranes with amorphous and crystallized Nb40Ti30Ni30 metal layer was measured and compared with that of self-supported Nb40Ti30Ni30 and Pd alloys. Solid-state diffusion was shown to be the rate-controlling factor when the thickness of the Nb40Ti30Ni30 layer was about 12 μm or greater, while other factors were in effect for thinner layers (such as 6 μm). The Pd/Nb40Ti30Ni30/Pd/porous nickel support composite membrane exhibited excellent permeation capability and satisfactory mechanical properties. It is a promising new permeation membrane that could replace Pd and PdAg alloys for hydrogen separation and purification. © 2009 Professor T. Nejat Veziroglu.


Luo J.-H.,CAS Shenyang Institute of Metal Research | Kang X.-D.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research
Journal of Physical Chemistry C | Year: 2010

Mechanically milling with the off-the-shelf magnesium (Mg) powder can dramatically improve the dehydrogenation properties of ammonia borane (AB) on all key aspects: enhancing the dehydrogenation kinetics, reducing the induction period, suppressing the formation of volatile byproduct, and alleviating the sample foaming. The postmilled AB/0.5Mg sample can release 8.2 wt % of hydrogen at 100 °C within 4 h and deliver >2.5 equiv of hydrogen in AB upon elevating the dehydrogenation temperature to 300 °C, giving a material-based hydrogen capacity of 12 wt %. Additionally, the dehydrogenation reaction of the AB/0.5Mg sample becomes significantly less exothermic than that of pristine AB, and remarkably, the third dehydrogenation step is tailored to be endothermic. Combination of phase/structure/chemical state analyses suggest that a considerable amount of Mg participates in the dehydrogenation process, resulting in the formation of Mg-N-B-H product(s). © 2010 American Chemical Society.


Cai D.,CAS Shenyang Institute of Metal Research | Chen J.,CAS Shenyang Institute of Metal Research | Mao X.,CAS Shenyang Institute of Metal Research | Hao C.,CAS Shenyang Institute of Metal Research
Intermetallics | Year: 2013

Serious reheat cracking susceptibility was found in Ti2AlNb alloy resistance spot weldments and the cracking mechanism was investigated in this work by means of hot ductility test and microstructure analysis. The results indicated that the precipitation of hardening phase (O phase) together with the residual stress have led to cracking during post-weld heat treatment in Ti2AlNb alloy resistance spot weldments. To prevent the reheat cracking, rapid heating schedule or mechanical stress relieving method was proposed and verified. © 2013 Elsevier Ltd. All rights reserved.


Xu J.,CAS Shenyang Institute of Metal Research | Wu X.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2012

The evolution of electrochemical behaviour and oxide film properties of 304 stainless steel in high temperature aqueous environment have been studied by polarization curves, electrochemical impedance spectra (EIS) and X-ray photoelectron spectroscopy (XPS). The electrochemical data indicate that the corrosion resistance of the steel increases with immersion time. The EIS and XPS analyses show that the oxide films are a duplex structure and the corrosion rate is dominated mainly by the Cr-rich inner layer. The correlation between the evolution of the electrochemical behaviour and the changes of the oxide film properties is discussed. © 2012 Elsevier Ltd. All rights reserved.


Ma L.-P.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2010

Identification of effective catalyst is a subject of great interest in developing MgH2 system as a potential hydrogen storage medium. In this work, the effects of typical titanium compounds (TiF3, TiCl3, TiO2, TiN and TiH2) on MgH2 were systematically investigated with regard to hydrogen sorption kinetics. Among them, adding TiF3 leads to the most pronounced improvement on both absorption and desorption rates. Comparative studies indicate that the TiH2 and MgF2 phases in situ introduced by TiF3 fail to explain the superior catalytic activity. However, a positive interaction between TiH2 and MgF2 is observed. Detailed comparison between the effect of TiF3 and TiCl3 additive suggests the catalytic role of F anion. XPS examination reveals that new bonding state(s) of F anion is formed in the MgH2 + TiF3 system. On the basis of these results, we propose that the substantial participation of F anion in the catalytic function contributes to the superior activity of TiF3. © 2009 Professor T. Nejat Veziroglu.


Wang P.-J.,CAS Shenyang Institute of Metal Research | Fang Z.-Z.,CAS Shenyang Institute of Metal Research | Ma L.-P.,CAS Shenyang Institute of Metal Research | Kang X.-D.,CAS Shenyang Institute of Metal Research | Wang P.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2010

Various carbon additives were mechanically milled with LiBH4/MgH2 composite and their hydrogen storage behaviors were investigated. It was found that most of the carbon additives exhibited prominent effect on the host material. Among the various carbon additives, purified single-walled carbon nanotubes (SWNTs) exhibited the most prominent effect on the kinetic improvement and cyclic stability of Li-Mg-B-H system. Results show that LiBH4/MgH2 composite milled with 10 wt.% purified SWNTs additive can release nearly 10 wt.% hydrogen within 20 min at 450 °C, which is about two times faster than that of the neat LiBH4/MgH2 sample. On the basis of hydrogen storage behavior and structure/phase investigations, the possible mechanism involved in the property improvement upon carbon additives was discussed. © 2009 Professor T. Nejat Veziroglu.


Shi J.,CAS Shenyang Institute of Metal Research | Wu E.,CAS Shenyang Institute of Metal Research
Microporous and Mesoporous Materials | Year: 2013

Mesoporous NiO is synthesized with a fast and facile method by using octylamine (OA) and NiCl2·6H2O as template and precursor, respectively. The resultant products are characterized with XRD, DRIFT, SEM, TEM, XPS and nitrogen adsorption-desorption measurements. The synthesis approach is described by the S+X-I+ (OA+Cl-Ni2+) assembly pathway, where the process is mediated by the addition of HCl. The reaction takes place at room temperature and completes in an hour, where the addition of NaOH solution leads to rapid precipitation of Ni(OH)2 and formation of partially ordered mesopores. Nanocrystalline mesoporous NiO is obtained after removal of template and decomposition of Ni(OH)2 upon hot ethanol washing and calcination. The mesopores in NiO are built from the embedded nanocrystallites through template removal and calcination induced cracking. The NiO product achieves a high surface area of 350 m2/g after 300°C/3 h calcination. The effects of synthetic conditions on the properties of NiO are addressed. © 2012 Elsevier Inc. All rights reserved.


Li W.,CAS Shenyang Institute of Metal Research | Liu J.,CAS Shenyang Institute of Metal Research | Yan C.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2012

Single-walled carbon nanotube (SWCNT) was used as an electrode catalyst for an all vanadium redox flow battery (VRFB). The electrochemical property of SWCNT towards VO 2 +/VO 2+ and V 3+/V 2+ was carefully characterized by cyclic voltammetric (CV) and electrochemical impedance spectroscopy (EIS) measurements. The peak current values for these redox pairs were significantly higher on the modified glassy carbon electrode compared with those obtained on the bare electrode, suggesting the excellent electrochemical activity of the SWCNT. Moreover, it was proved that the anodic process was more dependent on the surface oxygen of the SWCNT than the cathodic process through changing its surface oxygen content. Detailed EIS analysis of different modified electrodes revealed that the charge and mass transfer processes were accelerated at the modified electrode-electrolyte interface, which could be ascribed to the large specific surface area, the surface defects and the oxygen functional groups of the SWCNT. The enhanced battery performance effectively demonstrated that the SWCNT was suitable to serve as an electrode catalyst for the VRFB. © 2012 Elsevier Ltd.


Wang W.,CAS Shenyang Institute of Metal Research | Chen D.M.,CAS Shenyang Institute of Metal Research | Yang K.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2010

In order to study the effect of cooling rate on the microstructures and hydrogen generation performance of Al alloys, two ingots (20 g and 45 g) with a composition of 94 Al, 3.8 Ga, 1.5 In and 0.7 Sn (in mass%) were prepared by arc melting under high purity argon atmosphere, and a rod (10 g) with the same composition was cast in a vacuum chamber. The microstructures and phase compositions of the three samples were investigated by means of X-ray diffraction and scanning electron microscope with energy dispersed X-ray. The melting point of the grain boundary phase was measured using differential scanning calorimeter. Based on the structural analysis, samples with different but uniform grain sizes were cut from these alloys for H2 generation. The reactions of Al alloys with water were measured at different temperatures. The measured H2 generation rates were found to increase rapidly once the grain size was reduced below 50 μm. An isothermal kinetic model was employed to analyze the measured kinetic data so as to obtain kinetic parameters of reactions. The reaction order (n) for these alloys was found to be about 0.7. The activation energy (Ea) decreases with grain size d, i.e., 30% reduction of Ea as d was reduced from 258 to 23 μm. A mechanism of Al alloy corrosion in water was proposed. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.


Jiao Y.,CAS Shenyang Institute of Metal Research | Jiang C.,CAS Shenyang Institute of Metal Research | Yang Z.,CAS Shenyang Institute of Metal Research | Liu J.,Shenyang Jianzhu University | Zhang J.,CAS Shenyang Institute of Metal Research
Microporous and Mesoporous Materials | Year: 2013

Highly accessible porous ZSM-5 coating with high loading and high adherence was successfully grown on SiC foam support using a two-step coating and steam-assisted crystallization process. The zeolite precursor gel pre-coated on the SiC foam surface and existed in the upper mixed coating layer functioned as a binder to firmly bond the SiC support and the pre-coated zeolite crystals with the formation of a dense ZSM-5 transition layer. The high porosity was achieved from the pre-coated zeolite crystals. The ZSM-5/SiC foam composite catalyst prepared by the proposed method showed higher propylene selectivity and propylene to ethylene (P/E) ratio, lower C1-C4 saturated hydrocarbons and aromatics and as well as higher stability in comparison to that prepared by conventional in situ hydrothermal process in methanol to propylene reaction. © 2013 Elsevier Inc. All rights reserved.


Du B.,CAS Shenyang Institute of Metal Research | Yang J.,CAS Shenyang Institute of Metal Research | Cui C.,CAS Shenyang Institute of Metal Research | Sun X.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2015

The HCF (high-cycle fatigue) property of Ni-base cast superalloy IN792 with various grain sizes was investigated at 700. °C, 800. °C and 900. °C. The results show that grain refinement could improve the HCF lives since it could reduce the probability that "fatigue hot spots" initiate near the surface. The improvement effect of grain refinement on the HCF life decreases with the increase of temperature and applied loading amplitude due to that the increasing of temperature and applied loading amplitude would cause a transition of "fatigue hot spots" from the bulk to the surface or subsurface for fine grain specimens. The HCF deformation mechanism was studied through dislocation structure observation. At 700. °C, the movement of dislocations is restricted in the slip bands and the fatigue cracks form in a glide plane decohension manner, therefore it is easier to generate a fatigue crack for coarse grain specimens than fine grain specimens. As the temperature increased to 800. °C and 900. °C, the distribution of dislocations become more homogeneous and glide plane decohension is inhibited, so that the role of grain refinement on the HCF behavior is decreased. © 2014 Elsevier Ltd.


Wang X.,CAS Shenyang Institute of Metal Research | Chen M.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Journal of the American Ceramic Society | Year: 2013

Yttria partially stabilized zirconia Y-PSZ/glass-ceramic composites were prepared by reaction sintering using powder mixtures of a SiO 2-Al2O3-ZnO-CaO-ZrO2-TiO 2-based glass and yttria partially stabilized zirconia (Y-PSZ). The glass crystallized during sintering at temperatures of 1173, 1273, and 1373 K to give a glass-ceramic matrix for high-temperature protecting coatings. With the increasing firing time, the added zirconia reacted with the base glass and a glass-ceramic material with dispersed zircon particles was prepared in situ. Furthermore, the added zirconia changed the crystallization behavior of the base glass, affecting the shape, amount, and distribution of zircon in the microstructure. The bipyramid-like zircon grains with imbedded residual zirconia particles turned out to have two growth mechanisms: the inward growth and the outward growth, and its rapid growth was mainly dominated by the later one. For comparison, the referenced glass-ceramic was prepared by sintering using exclusive glass granules and its crystallization behavior at 1173-1373 K was examined as well. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the crystallization behavior of the base glass and the phase evolution of the Y-PSZ/glass-ceramic composites. © 2013 The American Ceramic Society.


Li C.-F.,CAS Shenyang Institute of Metal Research | Liu Z.-Q.,CAS Shenyang Institute of Metal Research | Shang J.-K.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2013

The effects of exposure time, temperature and humidity on the growth of tin whisker and hillock from Sn5Nd alloy were investigated via scanning electron microscopy. It was found that tin whiskers grew from NdSn3 compound, while hillocks grew from the tin matrix around the NdSn3 compound, which was induced by the oxidation of NdSn3 compound by oxygen and water vapor in the ambient. More tin whiskers and/or hillocks were extruded from the substrate with longer exposure time, higher temperature and higher humidity. This resulted in the formation of various morphologies of tin extrusions at different storage conditions, including thread-like, spiral, flute-like, claw-like, sprout-like, chrysanthemum-like and rod-like whiskers, as well as hillocks. Tin whisker was extruded from the crack of the surface Nd(OH)3 layer which serves as the mold of tin whisker growth. And the proposed growth models of tin whisker and hillock on Sn-Nd alloy can explain the diversity of the whisker morphology. © 2012 Elsevier B.V. All rights reserved.


Sun J.L.,Nanjing University of Science and Technology | Sun J.L.,University of Sydney | Trimby P.W.,University of Sydney | Si X.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Scripta Materialia | Year: 2013

The scanning electron microscopy transmission Kikuchi diffraction technique was used to characterize the microstructure of ultrafine-grained Ti processed by dynamic plastic deformation at room temperature. Contrary to the general conception that twinning plays little role in the plastic deformation of ultrafine-grained hexagonal close-packed Ti, nanocrystalline {112̄2} and {101̄2} deformation twins were widely observed in the material. The observation provides insight into the deformation mechanisms and mechanical behaviour of nanostructured metals with hexagonal close-packed structures. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Lin G.-M.,CAS Shenyang Institute of Metal Research | Xie G.-Y.,CAS Shenyang Institute of Metal Research | Sui G.-X.,CAS Shenyang Institute of Metal Research | Yang R.,CAS Shenyang Institute of Metal Research
Composites Part B: Engineering | Year: 2012

Polyetheretherketone (PEEK) composites reinforced with carbon fibers (CFs) and nano-ZrO2 particles were prepared by incorporating nanoparticles into PEEK/CF composites via twin-screw extrusion. The effects of nanoparticles on the mechanical and wear properties of the PEEK/CF composites were studied. The results showed that the incorporation of nano-ZrO2 particles with carbon fiber could effectively enhance the tensile properties of the composites. The tensile strength and Young's modulus of the composites increased with the increasing nano-ZrO2 content. The enhancement effect of the particle was more significant in the hybrid reinforced composites. The compounding of the two fillers also remarkably improved the wear resistance of the composites under water condition especially under high pressures. It was revealed that the excellent wear resistance of the PEEK/CF/ZrO2 composites was due to a synergy effect between the nano-ZrO2 particles and CF. CF carried the majority of load during sliding process and prevented severe wear to the matrix. The incorporation of nano-ZrO2 effectively inhibited the CF failures through reducing the stress concentration on the carbon fibers interface and the shear stress between two sliding surfaces. It was also indicated that the wear rates of the hybrid composites decreased with the increasing applied load and sliding distance under water lubrication. And low friction coefficient and low wear rate could be achieved at high sliding velocity. © 2011 Elsevier Ltd. All rights reserved.


Sun H.,CAS Shenyang Institute of Metal Research | Liu L.,CAS Shenyang Institute of Metal Research | Li Y.,CAS Shenyang Institute of Metal Research | Ma L.,Luoyang Ship Material Research Institute | Yan Y.,Luoyang Ship Material Research Institute
Corrosion Science | Year: 2013

The corrosion behaviour and working performance of Al-Zn-In-Mg-Ti sacrificial anode were studied in simulated deep water environment using potentiodynamic polarization, electrochemical impedance spectroscopy, self-discharge, gravimetric and imaging measurements. The results indicate that the corrosion of Al-Zn-In-Mg-Ti is accelerated which is due essentially to acceleration of the cathodic process, and the efficiency of Al-Zn-In-Mg-Ti sacrificial anode drops dramatically in deep water which is related to increased loss in weight and decreased discharge capacity. The corresponding cathodic protection design parameters of steel as calculate, show that at least 22% more Al-Zn-In-Mg-Ti anode should be required in deep water environment. © 2013 Elsevier Ltd.


Yuan J.,CAS Shenyang Institute of Metal Research | Wang W.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Oxidation of iron was investigated in oxygen and in steam at 650-750. °C by TGA, OM, SEM, and XRD. In oxygen, parabolic kinetics and multilayer oxide scales composed of typical three iron oxides were observed. Noticeably, the scale adhesion was very poor. In steam, linear-parabolic shape kinetics and multilayer oxide scales with fewer pores were found. As indicated by Pt marking, inward-growing process in steam was considered to result in the improvement of scale contact. Based on the experimental results, scaling mechanism of iron in steam was discussed. © 2013 Elsevier Ltd.


Qian Y.,CAS Shenyang Institute of Metal Research | Ma C.,Control Iron and Steel Research Institute, China | Niu D.,Northeastern University China | Xu J.,CAS Shenyang Institute of Metal Research | Li M.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

The influence of alloyed chromium on atmospheric corrosion resistance (ACR) of weathering steels in simulated industrial atmosphere was investigated. The ACR of weathering steels was evaluated by determining the relative corrosion rate after periodic immersion wet/dry cyclic corrosion for 72. h. The presence of Cr improves the ACR of weathering steels. The beneficial effect of alloyed chromium is attributed to both its promotion of the formation of a protective rust layer, which acts as a barrier against corrosion process, and its enhancement of passivation capability, which decreases the anodic dissolution of substrate alloys. © 2013.


Li W.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang C.,CAS Shenyang Institute of Metal Research | Chen M.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Corrosion Science | Year: 2013

A SiO2-Al2O3-glass composite coating was prepared on Ti-6Al-4V alloy by air spraying and subsequent firing. The oxidation behavior of the specimens at 800°C and 900°C for 100h was studied. The thermal shock resistance of the coating was tested by heating up to 900°C and then quenching in water. The composite coating acted as an oxygen migration barrier and exhibited good resistance against high temperature oxidation, thermal shock, and oxygen permeation on the Ti-6Al-4V alloy. Coating/alloy interfacial reaction occurred, forming a Ti5Si3/Ti3Al bilayer structure. A thin Al2O3 rich layer formed beneath the composite coating during oxidation at 900°C. © 2013 Elsevier Ltd.


Liu Y.,CAS Shenyang Institute of Metal Research | Wang J.,CAS Shenyang Institute of Metal Research | Liu L.,CAS Shenyang Institute of Metal Research | Li Y.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

The failure mechanisms of an epoxy varnish coating and an epoxy glass flake coating were investigated under ordinary pressure (1. atm) and high hydrostatic pressure (35. atm), from electrochemical behavior, water absorption, wet adhesion and mechanical characteristics. The results revealed that mechanical properties were more favorable under 35. atm, but pressure changed the electrochemical behavior and deteriorated coating protectiveness by accelerating water absorption, increasing diffusion coefficient and changing diffusion type. More importantly, loss of wet adhesion, induced by blisters and corrosion products on interface, became the main reason for coating failure and thus the key factor controlling coating lifetime. © 2013 .


Chen M.,CAS Shenyang Institute of Metal Research | Li W.,CAS Shenyang Institute of Metal Research | Shen M.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

A glass-ceramic coating is applied on Ti-6Al-4V alloy for oxidation protection at 800°C. Its dynamic oxidation and microstructure evolution are investigated. The titanium alloy substrate is effectively protected by the glass-ceramic coating, of which the oxidation develops at constant rate. The linear relationship of oxidation is deduced dm/dt=Dρ(C1-C2)/(bC'), and the diffusion coefficient of oxygen at 800°C in glass is obtained. Oxygen diffusion through glass coating is the controlling step. After the initial firing, silicide interlayer forms between the glass coating and titanium alloy substrate, where the ratio of Ti/Si decreases after oxidation due to Si diffusion and Ti consumption. © 2013 Elsevier Ltd.


Gao Z.-H.,CAS Shenyang Institute of Metal Research | Xu J.-J.,CAS Shenyang Institute of Metal Research | Zhang Z.-W.,Aerospace Research Institute of Materials And Processing Technology | Qian Y.-H.,CAS Shenyang Institute of Metal Research | Li M.-S.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

The effects of ZrB2 and ZrB2+SiC additions on the oxidation kinetics of graphite at 1600-2000°C in air were investigated. The ZrB2+SiC dual addition improves the oxidation resistance of graphite more effectively than the ZrB2 single addition, because the oxide scale formed on C-ZrB2-SiC is denser and thinner due to the existence of glassy SiO2. As the oxidation temperature increases, the oxidation rate of C-ZrB2-SiC gradually increases and oxide scales with layered microstructures form on its surface due to the greatly enhanced active oxidation of SiC at higher temperatures. © 2013 Elsevier Ltd.


Fan Q.X.,CAS Shenyang Institute of Metal Research | Jiang S.M.,CAS Shenyang Institute of Metal Research | Wu D.L.,CAS Shenyang Institute of Metal Research | Gong J.,CAS Shenyang Institute of Metal Research | Sun C.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Two Co modified aluminide coatings with different Co contents were prepared by a combined method of pack cementation and chemical vapour deposition. The type-I hot corrosion tests of the two Co modified coatings together with the simple aluminide coating were carried out at 900 °C. Results indicate that the addition of cobalt could improve the corrosion resistance of the coatings in the sulphate salts, but exacerbate the degradation of the coatings when chloride salt gets involved. The formation mechanism of the Co modified aluminide coatings and the corrosion mechanism during the corrosion test have been discussed as well. © 2013 Elsevier Ltd.


Wang C.,CAS Shenyang Institute of Metal Research | Wang W.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Inorganic silicate composite coatings on γ-TiAl were fabricated by air spraying. The oxidation behaviour of the alloy was investigated at 900°C. The results indicated that rapid oxidation occurred in the γ-TiAl, and multilayered non-protective TiO2 and Al2O3 scales formed. For coated γ-TiAl alloy, the oxidation was markedly inhibited; a thin Al2O3 layer was detected, which improved the oxidation resistance of the alloy. The low oxygen partial pressure at the interface of the coatings and the alloy promotes the preferentially oxidation of Al in the γ-TiAl substrate, and the outward diffusion of Ti to form TiO2 was retarded. © 2013 Elsevier Ltd.


Wang Z.M.,CAS Shenyang Institute of Metal Research | Wang Z.M.,Sinopec | Chang X.C.,CAS Shenyang Institute of Metal Research | Hou W.L.,CAS Shenyang Institute of Metal Research | Wang J.Q.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

The selective dissolution behaviour of CuZr-based metallic glasses can be strongly influenced by minor Ni additions. The surface corrosion layers of the Ni-free alloy are changed from a porous Cu-enriched film to a Zr-enriched covered passive film on the Ni-containing alloys, thus, resulting in the elevation of critical potentials. The results indicate that the preferential dissolution of Zr atoms is inhibited by minor Ni alloying, while Cu atoms dissolve. A local bonding controlled mechanism is proposed to understand the switchable behaviour of selective dissolution. It presents us with new insights into the intrinsic corrosion resistance of alloys. © 2013 Elsevier Ltd.


Zheng Z.B.,CAS Shenyang Institute of Metal Research | Zheng Y.G.,CAS Shenyang Institute of Metal Research | Sun W.H.,CAS Shenyang Institute of Metal Research | Wang J.Q.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Erosion-corrosion (E-C) behaviour of a Fe-based amorphous metallic coating (AMC) compared with 304 stainless steel (304 s.s.) was studied under a slurry impingement condition in a sand-containing NaCl solution. AMC exhibited much higher resistance to E-C than 304 s.s. The weight loss reached the maximum at an impact angle of 90° and the critical flow velocity was about 15. m/s for AMC, while 45° and 9. m/s for 304 s.s. The increment in passive current density under impingement for AMC was about 10 times lower than 304 s.s. Passive films formed at different impact velocities were of different thicknesses. © 2013 Elsevier Ltd.


Liu M.,Wuhan University | Mao X.,Wuhan University | Zhu H.,Wuhan University | Lin A.,Wuhan University | And 2 more authors.
Corrosion Science | Year: 2013

A two-step esterification process is developed for the synthesis of epoxy-acrylic-grafted-copolymer waterborne resins. The effect of synthesis parameters on water and corrosion resistance of the waterborne coatings is investigated. The results reveal that moderate increasing of the resin molecular weight (<8000. Da) and carboxyl content (<27. wt.%) increased the crosslinking property, thereby improved the anticorrosion performance of the coatings. Longer epoxy-octanoic hydrophobic chains can provide stronger shielding effect on the hydrophilic portion of the polymer matrixes. The polar group content in a waterborne resin can be optimized for better anticorrosion performance, whereas the optimal value is coating-specific. © 2013 Elsevier Ltd.


Wang S.G.,CAS Shenyang Institute of Metal Research | Wang S.G.,CAS International Center for Materials Physics | Sun M.,Shenyang University of Technology | Han H.B.,Shenyang Ligong University | And 3 more authors.
Corrosion Science | Year: 2013

The high-temperature oxidation of bulk nanocrystalline 304 stainless steel (BN-SS304) and its conventional polycrystalline counterpart (CP-SS304) in air at 900°C for 24h were studied by thermogravimetric analysis, X-ray photoelectron spectroscopy and scanning electron microscope. We studied the valence electron configurations of BN-SS304, CP-SS304 and their oxide scales by ultra-violet photoelectron spectroscopy. The high-temperature oxidation resistance of BN-SS304 was enhanced in both initial and isothermal oxidation, which was attributed to its larger work function and more chemical stability, its more chemically stable and compact oxide scale, its weaker O2 adsorption and diffusion, its weaker Cr and Mn atoms diffusions. © 2013 Elsevier Ltd.


Qin X.,CAS Shenyang Institute of Metal Research | Qin X.,University of Chinese Academy of Sciences | Wang J.,CAS Shenyang Institute of Metal Research | Xie J.,CAS Shenyang Institute of Metal Research | And 4 more authors.
Physical Chemistry Chemical Physics | Year: 2012

Improving electrochemical properties of hydrothermally synthesized LiFePO 4 powders is of immense technological significance and has been a subject of much scientific inquiry for many years. As reported previously, reversing the feeding sequence of starting materials and/or introducing ethylene glycol (EG) could significantly improve the electrochemical performance of hydrothermally synthesized LiFePO 4. However, the mechanism remains unclear. Here, we report a systematic study to understand the mechanism from viewpoints of crystal growth and defect concentration control. Combining the results of experimental and theoretical investigations, the improvement in electrochemical performance is attributed to simultaneous suppression of crystal growth along the [010] direction and reduced defect concentration of the antisite. The reduction in antisite defects is readily monitored by significant red shift of the infrared (IR) absorption band around 1000 cm -1 which is assigned to the symmetric stretching P-O vibration of the PO 4 tetrahedron, as indicated by theoretical calculation. With this knowledge in mind, an output as high as 450 g L -1 (autoclave volume), and an enhanced specific discharge capacity of 165 A h kg -1 (close to the theoretical unity of 170 A h kg -1) at 0.1 C are achieved. © the Owner Societies 2012.


Song Y.,CAS Shenyang Institute of Metal Research | Shan D.,CAS Shenyang Institute of Metal Research | Chen R.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2010

An environmentally friendly molybdate/phosphate black film for light absorption application was developed as an alternative to the chromate system on Mg-Zn-Y-Zr alloy. The microstructure, surface morphology, chemical composition, light absorbance and protection property of the black film were investigated. The initiation and growth mechanisms of the black film were also discussed. The black film consists of MoO2 and a fraction of Mg3(PO4)2. The MoO2 contributes to the black color and the Mg3(PO4)2 aims to improve the protection property. The experimental results indicate that the black film can provide not only high light absorbance but also corrosion protection to the Mg-Zn-Y-Zr substrate. The formation mechanism of the black film is associated with the electrochemical heterogeneity of the Mg-Zn-Y-Zr substrate. At the cathodic sites, MoO4 2- is reduced to MoO2 accompanying with the hydrogen evolution reaction. At the anodic sites, the dissolution of Mg2+ bonds with PO4 3- to form Mg3(PO4)2.. © 2010 Elsevier B.V.


Zhang Q.,Tsinghua University | Zhao M.-Q.,Tsinghua University | Tang D.-M.,CAS Shenyang Institute of Metal Research | Li F.,CAS Shenyang Institute of Metal Research | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2010

It's a gas I The structure of the halomethane-producing halo/thiocyanate methyltransferase enzyme from plants has been determined. The halide ion and the methyl group of S-adenosyl-L-methionine (SAM) were modeled into the active site (see picture; chloride: green sphere; SAM: C green, O red, S yellow, N blue), which indicated their predisposition for reaction. (Figure Presented) © 2010 Wiley-VCH Verlag GmbH & Co. KCaA.


Wan X.S.,CAS Shenyang Institute of Metal Research | Zhao S.S.,CAS Shenyang Institute of Metal Research | Yang Y.,CAS Shenyang Institute of Metal Research | Gong J.,CAS Shenyang Institute of Metal Research | Sun C.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2010

Cr-N coatings were deposited on 1Cr18Ni9Ti stainless steel in the pure N2 atmosphere by arc ion plating (AIP). The relationships between deposition parameters and coating properties were investigated. X-ray diffraction showed a phase transformation from CrN + Cr2N + Cr → CrN + Cr → CrN and the CrN preferred orientation changed from (200) to (220) as N2 pressure increased. Increasing bias voltage led to CrN preferred orientation changed from (200) to (220) and the formation of Cr2N. XPS results indicated that chemical composition of the coatings changed as N2 pressure increased but it changed little with bias voltage. The lower melting point of chromium nitride formed on target surface induced the increase of macroparticles and deposition rate with increasing N2 pressure; and bias voltage had an obvious effect on reducing macroparticles of the Cr-N coatings. Residual stresses were measured by substrate curvature technique, and the changing tendency coincided with the microhardness of the coatings. © 2009 Elsevier B.V. All rights reserved.


Shao Y.F.,LIAONING Technical University | Zhao X.,Liaoning University of Technology | Li J.H.,Liaoning University of Technology | Wang S.Q.,CAS Shenyang Institute of Metal Research
Computational Materials Science | Year: 2013

The incipient plasticity of Al (0 0 1) surface under a small cylindrical indenter is studied by using multiscale simulations. Results show that both reversible and irreversible plasticity occurs under the indenter. During the reversible stage, only a thin deformation twin is formed, and the plastically deformed surface will completely recover to undistorted state upon withdrawal of the indenter, otherwise, both a deformation twin and a few stacking fault ribbons are observed, and a permanent residual trace will remain on the surface, as a sign of the irreversible plasticity. Our findings suggest that the effects of some internal and external material parameters, such as indentation depth, lattice frictional force, and stacking fault energy, on the incipient surface plasticity are very important in some small contact issues. The contact force and pressure under the indenter are also analyzed. Results imply that the theoretical prediction of the critical force is suitable for estimating the beginning of reversible plastic deformation, not the onset of the irreversible plasticity. © 2011 Elsevier B.V. All rights reserved.


Zhu Q.,CAS Shenyang Institute of Metal Research | Wang S.-Q.,CAS Shenyang Institute of Metal Research
Applied Surface Science | Year: 2016

Halides are often present at electrochemical environment, they can directly influence the electrode potential or zero charge potential through the induced work-function change. In this work, we focused in particular on the halogen-induced work function change as a function of the coverage of fluorine, chlorine, bromine and iodine on Al2Au and Al2Pt (110) surfaces. Results show that the real relation between work function change and dipole moment change for halogens adsorption on intermetallic surfaces is just a common linear relationship rather than a directly proportion. Besides, the different slopes between fitted lines and the theoretical slope employed in pure metal surfaces demonstrating that the halogens adsorption on intermetallic surfaces are more complicated. We also present a weight parameter β to describe different factors effect on work function shift and finally qualify which factor dominates the shift direction. © 2015 Elsevier B.V. All rights reserved.


He B.,CAS Shenyang Institute of Metal Research | Wang Z.,CAS Shenyang Institute of Metal Research
ACS Applied Materials and Interfaces | Year: 2016

In this study, BaTiO3/Pb(Zr0.52Ti0.48)O3 (BTO/PZT) ferroelectric superlattices have been grown on the Nb-doped SrTiO3 (NSTO) single-crystal substrate by pulsed laser deposition, and their electrical properties were investigated in detail. The leakage current was reduced significantly in the BTO/PZT superlattices, and the conduction mechanism could be interpreted as the bulk-limited mechanism. In addition, a more symmetric hysteresis loop was observed in the BTO/PZT superlattices compared with the pure PZT and BTO films. The BTO/PZT superlattices with the modulation thickness of 9.8 nm showed remarkably improved dielectric properties with dielectric constant and loss of 684 and 0.02, respectively, measured at the frequency of 10 kHz. Based on these experimental results, it can be considered that the BTO/PZT interfaces play a very important role for the enhanced electrical properties of the BTO/PZT superlattices. © 2016 American Chemical Society.


Weng Z.,CAS Shenyang Institute of Metal Research | Su Y.,CAS Shenyang Institute of Metal Research | Wang D.-W.,University of Queensland | Li F.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Advanced Energy Materials | Year: 2011

A simple and scalable method to fabricate graphene-cellulose paper (GCP) membranes is reported; these membranes exhibit great advantages as freestanding and binder-free electrodes for fl exible supercapacitors. The GCP electrode consists of a unique three-dimensional interwoven structure of graphene nanosheets and cellulose fi bers and has excellent mechanical fl exibility, good specifi c capacitance and power performance, and excellent cyclic stability. The electrical conductivity of the GCP membrane shows high stability with a decrease of only 6% after being bent 1000 times. This flexible GCP electrode has a high capacitance per geometric area of 81 mF cm -2, which is equivalent to a gravimetric capacitance of 120 F g -1 of graphene, and retains >99% capacitance over 5000 cycles. Several types of fl exible GCP-based polymer supercapacitors with various architectures are assembled to meet the power-energy requirements of typical fl exible or printable electronics. Under highly fl exible conditions, the supercapacitors show a high capacitance per geometric area of 46 mF cm -2 for the complete devices. All the results demonstrate that polymer supercapacitors made using GCP membranes are versatile and may be used for fl exible and portable micropower devices. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang D.,CAS Shenyang Institute of Metal Research | Ni D.R.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Materials and Design | Year: 2014

2. mm thick Fe-18.4Cr-15.8Mn-2.1Mo-0.66N high nitrogen austenite stainless steel plate was successfully joined by friction stir welding (FSW) at 800. rpm and 100. mm/min. FSW did not result in the loss of nitrogen in the nugget zone. The arc-shaped band structure, consisting of a small amount of discontinuous ferrite aligning in the bands and fine austenite grains, was a prominent microstructure feature in the nugget zone. The discontinuous ferrite resulted from newly formed ferrite during welding and the remained ferrite, whereas the fine austenite grains were formed due to dynamic recrystallization of the initial austenite during FSW. The fine dynamically recrystallized grains in the nugget zone significantly increased the hardness compared to that of the base material. The strength of the joint was similar to that of the base material, with the joint failing in the base material zone. © 2014 Elsevier Ltd.


Chen J.,CAS Shenyang Institute of Metal Research
Journal of Materials Science and Technology | Year: 2014

Ferroelectric barium strontium titanate (BST) glass-ceramics doped with different content of La2O3 were prepared via the melt-quenching technique followed by controlled crystallization. The microstructures of crystallized samples were examined by X-ray diffraction and scanning electron microscopy. Dielectric properties were also investigated. The aliovalent substitution of Ba by La induced dispersion of semiconducting BaxSr1-xTiO3 crystallites sealed in a glassy silicate matrix, which increased the εr and loss tangent values of the BST glass-ceramic. The experimental results indicate that aliovalent substitution is an effective method to process glass-ceramics with better dielectric properties. © 2013.


Ni D.R.,Ryerson University | Ni D.R.,CAS Shenyang Institute of Metal Research | Chen D.L.,Ryerson University | Yang J.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2014

A semi-solid processed (thixomolded) Mg-9Al-1Zn magnesium alloy (AZ91D) was subjected to friction stir welding (FSW), aiming at evaluating the weldability and fatigue property of the FSW joint. Microstructure analysis showed that a recystallized fine-grained microstructure was generated in the nugget zone (NZ) after FSW. The yield strength, ultimate tensile strength, and elongation of the FSW joint were obtained to be 192. MPa, 245. MPa, and 7.6%, respectively. Low-cycle fatigue tests showed that the FSW joint had a fatigue life fairly close to that of the BM, which could be well described by the Basquin and Coffin-Manson equations. Unlike the extruded magnesium alloys, the hysteresis loops of FSW joint of the thixomolded AZ91D alloy were basically symmetrical, while the non-linear or pseudoelastic behavior was still present. The FSW joint was observed to fail in the BM section rather than in the NZ. Fatigue crack initiated basically from the pores at or near the specimen surface, and crack propagation was mainly characterized by fatigue striations along with the presence of secondary cracks. © 2013 Elsevier Ltd.


Sun J.L.,Nanjing University of Science and Technology | Sun J.L.,University of Sydney | Trimby P.W.,University of Sydney | Yan F.K.,CAS Shenyang Institute of Metal Research | And 3 more authors.
Acta Materialia | Year: 2014

A cylindrical hexagonal-close-packed Ti sample was pre-deformed by dynamic compression to produce coarse-grained and ultrafine-grained structures in different parts of the sample followed by further dynamic compression to failure, making it possible to explore the effect of stored strain and grain boundary energy on shear banding in the material. A long shear band that formed during the final compression process passed through a complete diagonal of the sample. Electron backscattered diffraction was used to systematically investigate the shear-banding-induced structural evolution. Results show that the original stored energy in the matrix plays a significant role in the competition between deformation-induced grain refinement and grain growth, which determines the final average grain size in a shear band. Shear banding leads to grain reorientation such that one close-packed 〈112̄0〉 direction and one 〈101̄0〉 direction in most grains are parallel to the local shear direction and the normal direction to the local shear plane, respectively. The grain orientation in the shear band favours prismatic 〈a〉 slip, while the texture in the matrix, which is a stable compression texture, benefits the basal 〈a〉 slip. The results advance our understanding of the shear banding behaviour in heterogeneous deformation conditions and also the overall mechanical behaviour of materials under dynamic compression. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Jiang B.,CAS Shenyang Institute of Metal Research | Jiang S.L.,CAS Shenyang Institute of Metal Research | Ma A.L.,CAS Shenyang Institute of Metal Research | Zheng Y.G.,CAS Shenyang Institute of Metal Research
Materials and Manufacturing Processes | Year: 2014

To prevent premature failure of heat exchanger tubes enduring rapid seawater flow, amorphous electroless Ni-P coatings were prepared on copper-nickel alloy (CuNi 90/10) substrates. The influence of post-deposition vacuum heat treatment at different annealing temperatures (190, 300, 400, 500, and 600°C) on the erosion-corrosion resistance of the annealed coatings was examined by X-ray diffraction, scanning electron microscopy, potentiodynamic polarization, and electrochemical impedance spectroscopy. It was found that precipitation of a crystalline phase took place in the coating matrix at 400°C. The highest microhardness was achieved for coatings undergoing heat treatment at 400°C due to the formation of the stable Ni3P phase. Electrochemical results indicated that all the Ni-P coatings present passivity and better corrosion resistance than the uncoated CuNi 90/10 substrate. The Ni-P coating treated at 500°C demonstrated the best erosion-corrosion resistance, which represented the optimization of the balance between erosion and corrosion resistance. © 2014 Taylor and Francis Group, LLC.


Ji J.,Jiangsu University | Niu Y.,CAS Shenyang Institute of Metal Research | Wu J.,Jiangsu University | Yu Z.,CAS Shenyang Institute of Metal Research
Surface Engineering | Year: 2014

Multilayered TiN coating, with a microstructure of stackered up sandwiches, was successfully prepared by hollow cathode discharge method. The columnar epitaxial growth was obviously suppressed by introduction of the multilayered microstructure in the coating. The adhesion and wear resistance of the multilayered TiN coating was compared with those of the conventional TiN coating. The adhesion of the TiN coating to the substrate and the wear resistance of the TiN coating are obviously improved by optimising structural design. The multilayered microstructure of the coating piles up the dislocations and also inhibits the bulk flaking behaviour. The wear mechanism of the multilayered TiN coating is the microarea detachment. © 2014 Institute of Materials, Minerals and Mining.


Wang M.,Northeastern University China | Wang M.,CAS Shenyang Institute of Metal Research | Abbineni G.,University of Oklahoma | Clevenger A.,University of Oklahoma | And 2 more authors.
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2011

New generation fluorophores, also termed upconversion nanoparticles (UCNPs), have the ability to convert near infrared radiations with lower energy into visible radiations with higher energy via a nonlinear optical process. Recently, these UCNPs have evolved as alternative fluorescent labels to traditional fluorophores, showing great potential for imaging and biodetection assays in both in vitro and in vivo applications. UCNPs exhibit unique luminescent properties, including high penetration depth into tissues, low background signals, large Stokes shifts, sharp emission bands, and high resistance to photobleaching, making UCNPs an attractive alternative source for overcoming current limitations in traditional fluorescent probes. In this article, we discuss the recent progress in the synthesis and surface modification of rare-earth doped UCNPs with a specific focus on their biological applications. From the Clinical Editor: Upconversion nanoparticles - a new generation of fluorophores - convert near infrared radiations into visible radiations via a nonlinear optical process. These UCNPs have evolved as alternative fluorescent labels with great potential for imaging and biodetection assays in both in vitro and in vivo applications. © 2011 Elsevier Inc.


Zhu Y.,Anshan Normal University | Zhang B.,CAS Shenyang Institute of Metal Research | Liu X.,CAS Dalian Institute of Chemical Physics | Wang D.-W.,University of New South Wales | Su D.S.,CAS Shenyang Institute of Metal Research
Angewandte Chemie - International Edition | Year: 2014

Non-precious Fe/N co-modified carbon electrocatalysts have attracted great attention due to their high activity and stability in oxygen reduction reaction (ORR). Compared to iron-free N-doped carbon electrocatalysts, Fe/N-modified electrocatalysts show four-electron selectivity with better activity in acid electrolytes. This is believed relevant to the unique Fe-N complexes, however, the Fe-N structure remains unknown. We used o,m,p-phenylenediamine as nitrogen precursors to tailor the Fe-N structures in heterogeneous electrocatalysts which contain FeS and Fe3C phases. The electrocatalysts have been operated for 5000 cycles with a small 39 mV shift in half-wave potential. By combining advanced electron microscopy and Mössbauer spectroscopy, we have identified the electrocatalytically active Fe-N6 complexes (FeN6, [FeIII(porphyrin)(pyridine)2]). We expect the understanding of the FeN6 structure will pave the way towards new advanced Fe-N based electrocatalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wu D.,CAS Shenyang Institute of Metal Research | Chen R.S.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2014

The microstructures and mechanical properties of a sand-cast Mg-Nd-Zn alloy in the as-cast, solution-treated and peak-aged conditions were investigated. The as-cast alloy was comprised of α magnesium matrix and Mg12Nd eutectic compounds. The eutectic compounds dissolved into the matrix and small Zr-containing particles precipitated at grain interiors, due to the solution treatment. After the solution treatment, two kinds of cooling manner, either cooling in air or quenching in water, were employed. It was worth noting that some basal precipitates formed in the matrix during the in-air cooling process after solution treatment, which led to the succedent weak ageing hardening response and low strength in peak-aged condition. The hardness, yield strength, ultimate tensile strength and elongation at room temperature, of the samples in the T61 condition, were HV81, 191MPa, 258MPa and 4.2%, respectively. When tensile tested at high temperature, they exhibited serrated flow. Moreover, the casting surface of the tensile testing bar also had a great influence on its mechanical properties. © 2014 Elsevier Ltd.


Zhang W.,CAS Shenyang Institute of Metal Research | Sun D.,Jilin University | Han L.,Volkswagen AG | Liu D.,Jilin University
Materials and Design | Year: 2014

Dissimilar materials of H220YD galvanised high strength steel and 6008-T66 aluminium alloy were welded by means of median frequency direct current resistance spot welding with employment of 4047 AlSi12 interlayer. Effects of interlayer thickness on microstructure and mechanical property of the welded joints were studied. The welded joint with interlayer employed could be recognised as a brazed joint. The nugget diameter had a decreased tendency with increasing thickness of interlayer under optimised welding parameters. An intermetallic compound layer composed of Fe2(Al,Si)5 and Fe4(Al,Si)13 was formed at the interfacial zone in the welded joint, the thickness and morphology of which varying with the increase of interlayer thickness. Reaction diffusion at the steel/aluminium interface was inhibited by introduction of silicon atoms, which restricted growth of Fe2(Al,Si)5. Tensile shear load of welded joints experienced an increased tendency with increasing interlayer thickness from 100 to 300μm, and the maximum tensile shear load of 6.2kN was obtained with interlayer thickness of 300μm, the fractured welded joint of which exhibiting a nugget pullout failure mode. © 2013 Elsevier Ltd.


Zhang Z.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Acta Materialia | Year: 2014

The microstructural evolution in the heat-affected zone (HAZ) of 5 mm thick friction stir welded (FSW) 2024Al-T351 joints during long-term natural aging and its effect on mechanical properties were investigated by a combination of transmission electron microscopy, atom probe tomography, differential scanning calorimetry and mechanical property tests. FSW thermal cycle resulted in two low hardness zones (LHZs) in the HAZ: LHZ I, near the nugget zone (NZ), with grain coarsening and the dissolution of Guinier-Preston-Bagaryatsky (GPB) zones and solute clusters, as well as the formation and coarsening of S (Al 2CuMg) phases; and LHZ II, far from the NZ, with the dissolution of GPB zones and solute clusters. After 4-12 months of natural aging, the hardness recovered in the LHZ II due to the increase in number densities of Cu-Mg, Cu and Mg clusters, while there was no obvious change in the microstructure and hardness in LHZ I. The tensile strength of FSW 2024Al-T351 joints increased as the welding speed increased from 100 to 400 mm min-1 and was weakly enhanced by the long-term natural aging, but was independent of the rotation rates from 400 to 1200 rpm. The FSW joints fractured along LHZ I under a low welding speed of 100 mm min-1. With the increase of the welding speed and the prolongation of natural aging time, the joints fractured at LHZ I, LHZ II or the interface of the NZ/thermo-mechanically affected zone. The variation in the fracture locations was rationalized based on the microstructural evolution. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Wan P.,CAS Shenyang Institute of Metal Research | Yuan C.,Liaoning University | Tan L.,CAS Shenyang Institute of Metal Research | Li Q.,Liaoning University | Yang K.,CAS Shenyang Institute of Metal Research
Composites Science and Technology | Year: 2014

Polymers, such as poly-l-lactide (PLLA) were the first materials to be used as commercial biodegradable and bioresorbable implant materials. However, the limitations were focused on low mechanical properties and acid degradation by-products which were concerned as the source of inflammation. In this work, hybrid composites incorporated PLLA with 3-7wt% magnesium and magnesium fluoride particles were developed to overcome drawbacks mentioned above as novel bioresorbable orthopedic implants. The morphology, mechanical and thermal properties, in vitro degradation and cytotoxicity assessment were analyzed by SEM, DSC, UTM, pH value monitoring and MTT. It was found that the tensile strength was slightly decreased with addition of Mg particles. The tensile fracture morphologies indicated that the interface adhesion between Mg particles and PLLA matrix could be contributed to the influence on mechanism property. The addition of Mg and MgF2 into PLLA was effective in neutralizing the acid environment caused by degradation by-products, which was reflected by a close pH value to body fluid. Moreover, cell viability showed better cytocompatibility of composites with the beneficial Mg ions release. Therefore, PLLA/magnesium and PLLA/magnesium fluoride hybrid composites had a promising potential for orthopedic implant application. © 2014 Elsevier Ltd.


Wang S.,CAS Shenyang Institute of Metal Research
Entropy | Year: 2013

Atomic structure models of multi-principal-element alloys (or high-entropy alloys) composed of four to eight componential elements in both BCC and FCC lattice structures are built according to the principle of maximum entropy. With the concept of entropic force, the maximum-entropy configurations of these phases are generated through the use of Monte Carlo computer simulation. The efficiency of the maximum-entropy principle in modeling the atomic structure of random solid-solution phases has been demonstrated. The bulk atomic configurations of four real multi-principal-element alloys with four to six element components in either BCC or FCC lattice are studied using these models. © 2013 by the authors; licensee MDPI, Basel, Switzerland.


Ni D.R.,CAS Shenyang Institute of Metal Research | Wang J.J.,CAS Shenyang Institute of Metal Research | Wang J.J.,Shenyang Aerospace University | Zhou Z.N.,Shenyang Aerospace University | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2014

Friction stir processing (FSP) was used to prepare NiTip reinforced 6061Al bulk composites with the aim to avoid deleterious Al-NiTi interface reaction occurred in cast and powder metallurgy processes. NiTip were homogeneously distributed in the Al matrix without interfacial reaction. The intrinsic characteristic of a reversible thermoelastic phase transformation of the NiTip was observed in the composites. The as-FSP composites showed lower tensile strengths and higher elongation than the as-received 6061Al-T651, and the strengths increased greatly after both aging and T6 heat treatments without interfacial products being detected. The results show that FSP is an effective way to produce NiTip/Al composites with good shape memory effect and mechanical properties. © 2013 Elsevier B.V. All rights reserved.


Chen Z.,CAS Shenyang Institute of Metal Research | Xu C.,CAS Shenyang Institute of Metal Research | Ma C.,CAS Shenyang Institute of Metal Research | Ren W.,CAS Shenyang Institute of Metal Research | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Advanced Materials | Year: 2013

A lightweight graphene foam composite with a density of 0.06 g/cm 3 is developed. It shows a EMI shielding effectiveness of 30 dB and specific shielding effectiveness of 500 dB·cm3/g, which surpasses the best values of metals and other carbon-based composites. In addition, the excellent flexibility of this foam composite gives it a stable EMI shielding performance under repeated bending. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhao Z.-S.,CAS Shenyang Institute of Metal Research | Xian A.-P.,CAS Shenyang Institute of Metal Research
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

The discovery processes of tin whiskers as well as the mechanism research and the prevention strategies were introduced. Meanwhile, some certain characteristics during the tin whisker growth, such as the polymorphism of morphology, the uncertainty in growth position, and so on, which had already been observed by some researchers were summarized. The tin whisker growth mechanisms proposed from the initial discovery stage to the present were reviewed, they are mainly the dislocation mechanism, the compressive stress mechanism, the recrystallization mechanism, the cracked oxide theory and the fresh tin atom mechanism. After making some comments on the problems of the theoretical models, some further suggestion for the whisker growth mechanism were put forward.


Hao Y.,CAS Shenyang Institute of Metal Research | Liu F.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research
Progress in Organic Coatings | Year: 2013

Polyaniline (PANI) was covered on the surface of ultra-short glass fibers uniformly by in situ polymerization of aniline. Epoxy coatings with different contents of PANI ultra-short glass fibers and ultra-short glass fibers were formulated and their protection abilities were evaluated by means of open-circuit potential, electrochemical impedance spectroscopy and salt spray test. The results showed that the PANI ultra-short glass fibers had a significant inhibitive effect and its best volume fraction was10% in epoxy coating. XPS results indicated that a dense, stable passive oxide film of Fe2O3/Fe3O4 was formed on the steel surface beneath the coating. © 2012 Elsevier B.V. All rights reserved.


Kuang W.,CAS Shenyang Institute of Metal Research | Wu X.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Characteristics of the oxide films formed on Alloy 690 under different dissolved oxygen (DO) concentrations in 290 °C water were examined. Under 3. ppm DO, the oxide film mainly consisted of outer spinel particles and porous NiO base layer. A thin Cr-rich film gradually develops with decreasing DO. Fe and Ni levels in the film decrease while Cr level increases concomitantly. The film preformed under high DO changes slightly when further immersed under low DO. The film preformed under low DO becomes much thicker when immersed under high DO, with gradual development of spinel particles and NiO base layer. © 2012 Elsevier Ltd.


Li X.,CAS Shenyang Institute of Metal Research | Wang J.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research | Ke W.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Corrosion behavior for Alloy 690 and Alloy 800 in simulated primary water is studied by open-circuit potential (OCP) measurement, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Rise of pressure and temperature lead to negative shift of corrosion potential for both Alloy 690 and Alloy 800. EIS results show that the effect of pressure on corrosion only exists in low-frequency region, while the effect of temperature presents at the entire frequency range. Alloy 690 shows a better corrosion resistance than Alloy 800 at present investigated conditions. © 2012 Elsevier Ltd.


Qian Y.H.,CAS Shenyang Institute of Metal Research | Niu D.,Northeastern University China | Xu J.J.,CAS Shenyang Institute of Metal Research | Li M.S.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

To investigate the influence of chromium content on corrosion characteristics of weathering steels, the electrochemical measurements were performed on the steels containing 0-9% Cr (wt.%) in NaHSO3 aqueous solution. The results indicated that the open circuit potential of these steels shifted to the positive direction remarkably, because the additions of Cr improved the passivation capability of the steels. The corrosion current density of the steels containing more than 7% Cr (wt.%) decreased significantly after pre-rusted treatment, implying the corrosion resistance could be enhanced by the formation of protective goethite rust layer. © 2013 Elsevier Ltd.


Chen M.,CAS Shenyang Institute of Metal Research | Shen M.,CAS Shenyang Institute of Metal Research | Zhu S.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research | Wang X.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

The oxidation behavior of K38G superalloy, which is mechanically polished or sand blasted and then coated with glass matrix composite coatings, is investigated at 1000. °C. Results indicate that sand blasting pre-treatment enhances the resistance to oxidation and spallation of the glass coatings on superalloys by promoting formation of an alumina interlayer. The most important factors favoring formation of this alumina interlayer are discussed in terms of that sand blasting not only changes the microstructure of alloy, it also modifies the alloy composition at surface by affecting the progressing of interfacial reactions between the superalloy substrates and glass coatings. © 2013 Elsevier Ltd.


Xu J.,CAS Shenyang Institute of Metal Research | Wu X.,CAS Shenyang Institute of Metal Research | Han E.-H.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Acoustic emission (AE) response of a sensitized 304 stainless steel during intergranular corrosion (IGC) and stress corrosion cracking (SCC) has been detected. Active dissolution and IGC can generate AE signals but the AE activity and amplitude are relatively low. The number of AE signals increases smoothly during the SCC process. The fracture mode is mixed intergranular and transgranular. Both plastic deformation and crack propagation are acoustic emissive during the transgranular cracking while during the intergranular cracking only plastic deformation in the vicinity of the crack tip contributes to the AE signals. © 2013 Elsevier Ltd.


Pan C.,CAS Shenyang Institute of Metal Research | Liu L.,CAS Shenyang Institute of Metal Research | Li Y.,CAS Shenyang Institute of Metal Research | Wang F.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2013

Pitting corrosion behavior of coarse crystalline (CC) 304ss and its nanocrystalline (NC) thin film have been investigated by electrochemical measurement and in situ AFM observation in 3.5% NaCl solution. Results show two effects of nanocrystallization on pitting corrosion behavior: (1) more frequent occurrence of metastable pits, but with lower probability of transition to stable pits, which is attributable to differences in morphologies of sulfur and manganese as well as outstanding repassivation ability of NC thin film; (2) nanocrystallization decreases stable pit generation rate and its propensity to form larger pit cavities, and modifies the morphology of stable pit cavity. © 2013 Elsevier Ltd.


Yan J.W.,CAS Shenyang Institute of Metal Research | Zhu X.F.,CAS Shenyang Institute of Metal Research | Yang B.,CAS Shenyang Institute of Metal Research | Zhang G.P.,CAS Shenyang Institute of Metal Research
Physical Review Letters | Year: 2013

Severely localized deformation within shear bands can occur much more easily in a metal with nanoscale microstructures, such as nanograined and nanolayered materials. Based on atomic-scale observations, here we show that such locally large deformation (the continuous thinning of the layers) within the indentation-induced shear bands of the Cu/Au nanolayers is essentially attributed to the large shear stress component along the interface, which can refresh the capability of the interface to absorb incoming dislocations through unlocking the product of the dislocation-interface reaction. The results have implications for understanding the interface-mediated mechanisms of plastic deformation and for the engineering application of severe plastic deformation processing of metals at nanoscales. © 2013 American Physical Society.


He S.,Beijing University of Chemical Technology | Li C.,Beijing University of Chemical Technology | Chen H.,Beijing University of Chemical Technology | Su D.,CAS Shenyang Institute of Metal Research | And 6 more authors.
Chemistry of Materials | Year: 2013

How to achieve supported metal nanocatalysts with simultaneously enhanced activity and stability is of vital importance in heterogeneous catalysis and remains a challenging goal. In this work, a surface defect-promoted Ni nanocatalyst with a high dispersion and high particle density embedded on a hierarchical Al2O3 matrix was fabricated via a facile method involving an in situ reduction process, which exhibits excellent activity and stability simultaneously for the reaction of CO2 methanation. HRTEM, HAADF-STEM, EXAFS, and positron annihilation spectroscopy demonstrate the existence of abundant surface vacancy clusters that serve as active sites, accounting for the significantly enhanced low-temperature activity of the supported Ni nanoparticles. In addition, the anchoring effect from the support gives rise to a high reaction stability, without sintering and/or aggregation of active species during long-term use. © 2013 American Chemical Society.


Zhao J.X.,CAS Shenyang Institute of Metal Research | Zhao J.X.,Chinese Academy of Sciences
Philosophical Magazine Letters | Year: 2016

Qualitative and quantitative models were proposed to understand the shear band (SB) interaction scenario found in the compressive tests on specimen with two symmetrical semi-circular notches. The so-called ‘work-hardening’ behavior could be ascribed as the stress interaction which was caused by stress fields around the SB tips. Besides, the SB bending was observed along propagation orientation. The quantitative analysis based on traditional shear deformation mechanism could reasonably account for how the SB was bent. It is anticipated that the present work could provide a pathway to understand the deep SB deformation mechanism of metallic glass. © 2016 Taylor & Francis


Liu H.S.,CAS Shenyang Institute of Metal Research | Zhang B.,Northeastern University China | Zhang G.P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Here we reveal that a Cu/Cu laminated composite with an appropriate mechanical contrast between constituent layers can effectively improve the toughness and fatigue strength of cold rolled Cu. The local interface delamination-induced retardation of cracking and the secondary initiation of fatigue cracks at inner layer surfaces are the main mechanisms. Such the single material laminated with mechanical contrast provides a potential way to improve fatigue strength. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Chen X.H.,CAS Shenyang Institute of Metal Research | Chen X.H.,Chongqing University | Lu L.,CAS Shenyang Institute of Metal Research | Lu K.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

We investigate the grain size dependence of tensile behaviors of nanotwinned Cu with fixed twin thickness. With an increased grain size, ductility and work hardening of nanotwinned Cu are effectively promoted, but strength is not sacrificed to any notable degree. This may be attributed to the highly anisotropic plastic deformation of nanoscale twins. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Liu H.S.,CAS Shenyang Institute of Metal Research | Zhang B.,Northeastern University China | Zhang G.P.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

A cold-rolled metal sheet is usually of high strength but low plasticity due to the onset of premature local necking. Here, we reveal that the tensile plasticity of cold-rolled Cu can be effectively enhanced by a layered structure stacked alternately by thicker Cu and thinner Al layers. The layer interface in the composite strongly constrains and delays the development of premature local necking of the cold-rolled Cu layer. A potential way to improve plasticity without losing strength is suggested. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Zhang Q.K.,CAS Shenyang Institute of Metal Research | Zou H.F.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Journal of Electronic Materials | Year: 2011

In this study, the influences of substrate alloying and reflow temperature on the Bi segregation behaviors at the Sn-Bi/Cu interface were investigated. Cu and Cu-Ag alloys with different Ag contents were reflowed with Sn-Bi solder at 180°C, 200°C or 220°C, and then aged at 120°C for different times. The evolution of their interfacial morphologies during the aging process was observed, and tensile tests of some solder joints were conducted. The experimental results reveal that the Bi atoms that dissolved in the Cu 6Sn 5 during the reflow process are expelled when the Cu 6Sn 5 transforms into Cu3Sn and then segregate around the Cu 3Sn/Cu interface, inducing interfacial embrittlement. Alloying the Cu substrate with Ag can alleviate the Bi segregation by suppressing Cu 3Sn formation and dissolving the Bi atoms in the Cu-Ag substrate; the critical Ag content to eliminate the Bi segregation is about 1 at.% for the interface reflowed at 200°C. For interfaces reflowed at 180°C, the Bi segregation is less serious because less Bi is dissolved in the Cu 6Sn 5, and 0.6 at.% Ag can eliminate it. Tensile tests demonstrate that the embrittlement will not occur at Sn-Bi/Cu-Ag joints once the Bi segregation is eliminated. Based on this understanding, aging embrittlement of Sn-Bi/Cu solder joints can be prevented by decreasing the reflow temperature and adding a small amount of Ag to the Cu substrate. © 2011 TMS.


Zhou Y.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Superalloy CMSX-4 is directionally solidified and initiated by bicrystal seeds. It has been found that diverging boundaries are the most favorable location for stray grain formation. The phenomenon cannot be attributed to nucleation of crystals. A reasonable mechanism is the bending or detachment of side arms during extension of secondary arms and the development of tertiary branches at the diverging boundaries. Solute interaction of the neighboring dendrites increases the likelihood of bending or detachment and thus leads to an enhanced frequency of stray grains. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Li Y.,CAS Shenyang Institute of Metal Research
Materials China | Year: 2016

Facing the development of modern society and its economy,demands on metallic materials'propertis are ever increasing,including high strength and toughness, high wear resistance, high corrosion resistance, and high fatigue performance, et al. Gradient materials are a kind of materials that change gradually with a gradient from one constituent to another, including composition gradient, phase gradient, and grain size gradient or combination of the above. The gradient structures not only could effectively avoid the sudden change in properties caused by interface, but also coordinate the deformation of various feature sizes, and achieve the improvement of strength and ductility at the same time. In this paper, the concept and classification of the gradient materials are introduced, and the possible ways to produce gradient materials and the mechanism to improve multiple material properties are discussed. As one of the promising areas, gradient materials are expected to achieve the major advances in improving materials' properties and multifunctionality, and widely to be used in the application in near future. © 2016, The Editorial Board of Materials China. All right reserved.


Li L.L.,CAS Shenyang Institute of Metal Research | Zhang Z.J.,CAS Shenyang Institute of Metal Research | Zhang P.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Two kinds of Cu bicrystals, with a high-energy grain boundary (GB) and a coherent twin boundary (TB) parallel to the loading direction respectively, were cyclically deformed to reveal the fatigue cracking mechanisms. It is shown that intergranular fatigue cracking occurred firstly in the bicrystal with the GB, while the persistent slip bands became the preferential cracking sites in the bicrystal with TB. These results indicate that the TB has an intrinsically higher fatigue cracking resistance than the GB. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Li C.F.,CAS Shenyang Institute of Metal Research | Liu Z.Q.,CAS Shenyang Institute of Metal Research | Shang P.J.,CAS Shenyang Institute of Metal Research | Shang J.K.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

An in situ ex-environmental transmission electron microscopy (TEM) study was carried out to investigate the oxidation behavior of RESn3 (RE = Nd, La, Ce) film in a room at 18 ± 2 °C with 20 ± 5% humidity. The original RESn3 compounds transformed into RE(OH)3 nanocrystals and Sn clusters. This involved the selective oxidation of RE in RESn3 and the atomic diffusion of Sn atoms. The whole oxidation behavior was discussed from the thermodynamic viewpoint, and a reaction formula was proposed to summarize the oxidation of RESn3 under different ambient conditions. © 2011 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.


Hamad B.,University of Jordan | Hu Q.-M.,CAS Shenyang Institute of Metal Research
Physica Status Solidi (B) Basic Research | Year: 2011

Density functional theory (DFT) calculations were performed by using FP-LAPW method to investigate the effect of defects on the electronic and magnetic structure of Fe2MnSi Heusler alloy. The formation energies were calculated for antisite, swap, and vacancy defects. We found that three defects, namely MnFe and MnSi antisite as well as Fe-Mn swap defects may spontaneously occur as they have negative formation energies. Whereas, Mn and Si vacancies, Fe-Si swap, and FeMn antisite defects are unlikely to occur. However, the rest of the defects (FeSi, MnSi, and SiFe) antisites, Mn-Si swap, and Fe vacancy defects have relatively low formation energies that suggest higher probabilities to occur. The band gaps of the defected structures are found to be smaller than the ideal structure with almost zero values in the cases of FeSi antisite and Fe-Si swap defects. The structure with Fe vacancy defect, however, exhibits almost the same energy gap as that of the ideal structure. The magnetic structure was also affected by the presence of defects except for Fe-Mn and Mn-Si swap defects that show the same total magnetic moment of 3μB/f.u. as the ideal structure. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xue P.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Zhang Q.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Scripta Materialia | Year: 2011

Friction stir welded (FSW) pure copper joints with nearly equal strength to the parent metal were obtained at 400 rpm/50 mm min-1 via additional rapid cooling with flowing water. Significantly reduced heat input with a peak temperature of 130 °C and duration of 4 s above 100 °C in the thermal cycle was achieved in the heat-affected zone, resulting in the retainment of the original high dislocation density of the parent metal. This work provides an effective strategy to enhance the strength of FSW joints. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Centi G.,Messina University | Perathoner S.,Messina University | Su D.S.,CAS Shenyang Institute of Metal Research
Catalysis Surveys from Asia | Year: 2014

Nanocarbons find increasing relevance for the development of advanced, sometimes radically new, catalysts and catalytic electrodes. This perspective contribution discusses the potential of nanocarbons as a new class of catalytic materials, even if carbons (in the form mainly of active carbon materials) are already extensively applied as supports for catalysts. The control of nano-dimension and the improved understanding in tailoring the surface reactivity open new possibilities for their nano-engineering and the development of novel catalytic materials. With focus on the nature of the active sites in nanocarbon catalysts, we discuss here some of the novel possibilities opened by these materials to address the new challenges for catalysis deriving from moving to a more sustainable chemical and energy production. © 2014, Springer Science+Business Media New York.


Li W.,CAS Shenyang Institute of Metal Research | Liu J.,CAS Shenyang Institute of Metal Research | Yan C.,CAS Shenyang Institute of Metal Research
Carbon | Year: 2013

Electrochemically reduced graphene oxides (ERGO) are obtained under various reducing potentials in the phosphate buffer solution (PBS). Different characterization methods are used to analyse the changes of structure and surface chemical condition for graphene oxide (GO). The results show that GO could be reduced controllably to certain degree and its electrochemical activity towards VO2 +/VO2+ and V3+/V 2+ redox couples is also tunable using this environmentally friendly method. The catalytic mechanism of the ERGO is discussed in detail, the CO functional groups other than the C-O functional groups on the surface of ERGO more likely provide reactive sites for those redox couples, leading to a more comprehensive understanding about the catalytic process than previous relevant researches. This controllable modification method and the ERGO as electrode reaction catalyst with enhanced battery performance are supposed to have promising applications in the all vanadium redox flow battery. © 2012 Elsevier Ltd. All rights reserved.


Su Y.,CAS Shenyang Institute of Metal Research | Pei S.,CAS Shenyang Institute of Metal Research | Du J.,CAS Shenyang Institute of Metal Research | Liu W.-B.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Carbon | Year: 2013

Patterning is an essential and important process for the future use of single-walled carbon nanotube (SWCNT) thin films (TFs) in electronic devices. Different from traditional Si based electronic materials, SWCNTs can be easily etched when exposed to an oxidative atmosphere. Here we propose a gas exposure method to pattern SWCNT TFs on flexible polymeric substrates, without using vacuum and high temperature treatment. By simply exposing them to ozone for 3 min, a high quality SWCNT TF (35-40 nm in thickness) pattern is obtained on a poly (ethylene terephthalate) substrate. It is found that the ozone can chemisorb on, functionalize and etch SWCNTs and then destroy the electrically conductive network of SWCNT TFs, which causes a fast resistance increase and achieves efficient SWCNT TF patterns. The proposed patterning method has the advantages of high efficiency, low cost and scale-up ability, and more importantly, it is suitable for assembling flexible electronic devices, indicating prospects for the low-cost and large-scale manufacture of such items. © 2012 Elsevier Ltd. All rights reserved.


Yang R.,CAS Shenyang Institute of Metal Research
TMS Annual Meeting | Year: 2014

Recent activities of γ-TiAl related research at IMR is reviewed in this paper. On the fundamental side, first principles computations were performed to relate site occupancies and atomic interactions to the mechanisms of strengthening and phase transformation, and to understand surface adsorption of oxygen and oxidation. Deformation fundamentals such as nucle-ation of superdislocations in the γ phase were studied through molecular dynamics modeling. Our application-oriented work covers extrusion and net-shape forming that includes both precision casting and powder metallurgy. The evolution of textures during the coupled process of deformation, phase transformation, recrystallization and grain growth during extrusion and subsequent heat treatment was characterized and related to mechanical properties. Centrifugal casting was employed to obtain quality parts having thin sections but large size in 1- or 2-dimensions, and the problems such as misrun, cavities, surface porosity and inclusion as well as dimension distortion were tackled. Powder metallurgy was studied essentially as a technology upgrade of precision casting, forming components of complex shape.


Liu Z.Y.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Wang W.G.,CAS Shenyang Institute of Metal Research | Wang W.G.,Liaoning University | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Carbon | Year: 2013

A route combining friction stir processing and subsequent rolling processing was established to fabricate 1.5-4.5 vol.% carbon nanotube (CNT)-reinforced 2009Al composites. Microstructural observations indicated that CNTs were individually dispersed and directionally aligned in the aluminum matrix of the CNT/2009Al composites. The tube structure of the CNTs was retained and the CNT-Al interface was bonded without pores. As a result, great increases in yield strength, ultimate tensile strength, and Young's modulus were achieved when a higher concentration of CNTs was incorporated. Moreover, the composites exhibited good ductility. In particular, 3 vol.% CNT/2009Al composite exhibited an ultimate tensile strength of 600 MPa and elongation of 10%, much higher strength-ductility than the corresponding values for CNT/Al composites fabricated by other processes. © 2013 Elsevier Ltd. All rights reserved.


Cui J.W.,CAS Shenyang Institute of Metal Research | Calin M.,Leibniz Institute for Solid State and Materials Research | Eckert J.,Leibniz Institute for Solid State and Materials Research | Eckert J.,TU Dresden | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Applied Physics Letters | Year: 2013

Under tensile tests of metallic glasses (MGs) subjected to annealing below glass transition temperature Tg, ductile-to-brittle transition (DBT) occurs due to structural relaxation, which results in more ordered atomic packing and decrease of glass fraction φ. DBT is observed simultaneously with fracture mechanism transition: shear banding to cracking. All MG samples annealed under different temperature were also restricted to shear banding and cracking separately under small-aspect-ratio compression and compact tension avoiding DBT. Experimental results prove that as annealing temperature increases (or glass fraction φ decreases), strength for shear banding increases, while strength for cracking decreases; as φ becomes less than critical state φ D B T, MG samples tend to cracking instead of shear banding. So, φ D B T is proposed as an important parameter to characterize the intrinsic plasticity of various MGs and to conform to the previous factors soundly. © 2013 American Institute of Physics.


Zheng Z.,Central South University of forestry and Technology | Yu Z.,CAS Shenyang Institute of Metal Research
Surface and Coatings Technology | Year: 2010

The Ti(Y)N coatings were successfully deposited onto 18-8 stainless steel substrates by the hollow cathode discharge ion-plating method. The influence of the rare-earth element yttrium on the TiN coating properties was studied. The results show that the adhesion of the coating to the substrate were evidently enhanced by adding a small amount (0.2wt.%) of the rare-earth element yttrium, showing a critical load of about 390g which is much higher than that (230g) of the TiN coating/substrate. Investigation on the corrosion resistance of the Ti(Y)N coating and the TiN coating was performed in 0.5N Na 2SO 4+0.1N H 2SO 4+0.1N NaCl corrosion media by means of an electrochemical potentiodynamic polarization. The Ti(Y)N coating exhibited much better corrosion resistance than the TiN coating, whose passivity maintaining current is about one order in magnitude smaller than that of the TiN coating.The Ti(Y)N coatings deposited on some HSS-based tools were presented and compared with the TiN coating. The service lifetime of Ti(Y)N coated tools is approximately 36% higher (on the pinion shape cutters) and about 50% higher (on punch side pin) compared to that of TiN coated. The Ti(Y)N coatings showed such excellent performance. It is attributed to that the transition area of Ti(Y)N/substrate consisted of three sublayers which revealed a gradual change of phase structure and composition, so that the adhesion of the coating/substrate was evidently enhanced. Moreover, Ti(Y)N coating showed a preferred orientation with (111) plane which is favorable to improve wear resistance and corrosion resistance of the coating. © 2010 Elsevier B.V.


Wu S.,CAS Shenyang Institute of Metal Research | Wu S.,University of Chinese Academy of Sciences | Wen G.,CAS Shenyang Institute of Metal Research | Liu X.,CAS Dalian Institute of Chemical Physics | And 2 more authors.
ChemCatChem | Year: 2014

The role of different oxygen functional groups on a carbon catalyst was studied in the reduction of nitrobenzene by using a series of model molecules. The carbonyl and hydroxyl groups played important roles, which may be ascribed to their ability to activate hydrazine. In comparison, the ester, ether, and lactone groups seemed to be inactive, whereas the carboxylic group had a negative effect. The reaction occurred most likely through a direct route, during which nitrosobenzene may be converted directly into aniline. Modeling carbon: Thanks to model molecules, the carbon-catalyzed reduction of nitrobenzene is mimicked. The role of different oxygen functional groups on a carbon catalyst is studied, and the carbonyl and hydroxyl groups seem to be the most important moieties, which may be ascribed to their ability to activate hydrazine. The reaction occurs more likely through a direct route, during which nitrosobenzene may also be converted directly into aniline. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhao J.X.,CAS Shenyang Institute of Metal Research | Zhang Z.F.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering A | Year: 2011

Compressive tests on the Zr- and Ti-based metallic glasses with different notches were investigated to compare their shear fracture mechanism and plastic deformation abilities. It is found that the plasticity of the two metallic glasses can be improved by installing two semicircular symmetrical notches even for the Ti-based metallic glass which has nearly zero compressive plasticity. The enhanced plasticity may be ascribed to the easy initiation of shear bands (SBs) around the notches, and the consequent blocking effect of notches on the propagation of shear bands according to the large-scale stress gradient. Additionally, based on a theoretical model originated from the concept of critical steady shear displacement (CSSD), compared with the sizes of smooth regions on the fracture surface, the plasticity difference of the two different metallic glasses was analyzed quantitatively. The current findings might provide an approach to understand and estimate the difference in the plastic deformation abilities on diverse metallic glasses, as well as the ones with large-scale stress gradient. © 2010 Elsevier B.V.


Zhang X.X.,CAS Shenyang Institute of Metal Research | Xiao B.L.,CAS Shenyang Institute of Metal Research | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

In Part II of this series of articles, the transient thermal model, which was introduced in Part I, is used to explore the effects of welding conditions on the heat generation and temperature. FSW of the 6061-T651 aluminum alloy is modeled to demonstrate the model. The following two steps are adopted to study the influence of welding conditions on the heat generation and temperature. First, the thermal model is used to compute the heat generation and temperature for different welding conditions, the calculated results are compared with the reported experimental temperature, and a good agreement is observed. Second, the analytical method is used to explore the approximate functions describing the effect of welding conditions on the heat generation and temperature. Based on the computed results, we discuss the relationship between the welding conditions, heat generation, temperature, and friction coefficient, and propose a relationship map between them for the first time at the end. © 2011 The Minerals, Metals & Materials Society and ASM International.


Wu L.-K.,Zhejiang University | Hu J.-M.,Zhejiang University | Zhang J.-Q.,Zhejiang University | Zhang J.-Q.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2012

Organosilane/zinc composite films are prepared by one-step electrodeposition onto cold-rolled steels for corrosion protection. Electrochemical impedance spectroscopy measurement, bulk solution immersion and wet heat tests all show that the composite films have improved corrosion performance. X-ray photoelectron spectroscopy measurement suggests the successful encapsulation of metallic zinc. The embedding of metallic zinc results in negative shift in open-circuit potential of the film-covered electrodes. Such cathodic protection effect given by the metallic zinc provides the improved corrosion resistance of the composite films. © 2012 Elsevier Ltd.


Wang D.P.,CAS Shenyang Institute of Metal Research | Wang S.L.,CAS Shenyang Institute of Metal Research | Wang J.Q.,CAS Shenyang Institute of Metal Research
Corrosion Science | Year: 2012

The effect of amorphous structure on corrosion is a long-term puzzling problem. To elucidate this relationship, a Zr 2Ni metallic glass and its single crystal counterpart were selected, in which they are both homogeneous in composition and structure. The corrosion behaviour has been evaluated in 0.1M NaCl aqueous solution. Compared with the single crystal, the amorphous alloy presents a higher corrosion resistance. The passive film formed on the amorphous alloy contains more ZrO 2 and less NiO content. These results reflect that the amorphous structure could effectively influence the composition and compactability of passive films. © 2012 Elsevier Ltd.