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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

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.

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.

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.

Zhang T.,Xian University of Science and Technology | Zhao H.,Xian University of Science and Technology | He S.,Xian University of Science and Technology | Liu K.,Xian 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.

Mi S.-B.,Julich 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.

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.

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.

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.

Feng A.H.,Ryerson University | Chen D.L.,Ryerson University | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

Microstructural changes and cyclic deformation characteristics of friction-stir-welded 7075 Al alloy were evaluated. Friction stir welding (FSW) resulted in significant grain refinement and dissolution of η′ (Mg(Zn,Al,Cu)2) precipitates in the nugget zone (NZ), but Mg 3Cr2Al18 dispersoids remained nearly unchanged. In the thermomechanically affected zone (TMAZ), a high density of dislocations was observed and some dislocations were pinned, exhibiting a characteristic Orowan mechanism of dislocation bowing. Two low-hardness zones (LHZs) between the TMAZ and the heat-affected zone (HAZ) were observed, with the width decreasing with increasing welding speed. Cyclic hardening and fatigue life increased with increasing welding speed from 100 to 400 mm/min, but were only weakly dependent on the rotational rate between 800 and 1200 rpm. The cyclic hardening of the friction-stir-welded joints exhibiting a two-stage character was significantly stronger than that of the base metal (BM) and the energy dissipated per cycle decreased with decreasing strain amplitude and increasing number of cycles. Fatigue failure occurred in the LHZs at a lower welding speed and in the NZ at a higher welding speed. Fatigue cracks initiated from the specimen surface or near-surface defects in the friction-stir-welded joints, and the initiation site exhibited characteristic intergranular cracking. Crack propagation was characterized by typical fatigue striations along with secondary cracks. © 2010 The Minerals, Metals & Materials Society and ASM International.

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

Organosilanes are incorporated into a commercial cathodic electrophoretic paint, resulting in significant improvement in the long-term corrosion protective properties of the paint. The addition of organosilanes have strengthened mechanical properties, improved hydrophobicity, lowered water uptake and less decrease in glass transition temperature of the coatings, suggesting the enhancement in bulk structure of the polymeric coatings. In addition, silane-enriched layer preferentially forms at the metal/coating interface during the electrophoresis process, leading to better adhesion between the substrate and the coating. The structural enhancement in both the coating and the metal/coating interface explains the improved corrosion performance of silane-incorporated electrophoretic coatings. © 2011 Elsevier Ltd.

Yu R.,Tsinghua University | Hu L.H.,Tsinghua University | Cheng Z.Y.,Tsinghua University | Li Y.D.,Tsinghua University | And 2 more authors.
Physical Review Letters | Year: 2010

Using aberration-corrected transmission electron microscopy combined with first-principles calculations, we show that the surface structure of Co 3O4, a typical complex oxide, can be directly imaged and quantitatively analyzed at the subangstrom scale. The atomic positions of both light oxygen and heavier cobalt within the surface layers have been measured to an accuracy of several picometers. The surface electronic structure analysis suggests a polarity compensation model based on the electronic polarizability of surface ions. © 2010 The American Physical Society.

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.

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.

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.

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.

Tessonnier J.-P.,Fritz Haber Institute of the Max Planck Society | Tessonnier J.-P.,University of Delaware | Su D.S.,Fritz Haber Institute of the Max Planck Society | Su D.S.,CAS Shenyang Institute of Metal Research
ChemSusChem | Year: 2011

Tremendous progress has been achieved during the past 20 years on not only improving the yields of carbon nanotubes and move progressively towards their mass production, but also on gaining a profound fundamental understanding of the nucleation and the growth processes. Parameters that influence the yield but also the quality (e.g., microstructure, homogeneity within a batch) are better understood. The influence of the carbon precursor, the reaction conditions, the presence of a catalyst, the chemical and physical status of the latter, and other factors have been extensively studied. The purpose of the present Review is not to list all the experiments reported in the literature, but rather to identify trends and provide a comprehensive summary on the role of selected parameters. The role of the catalyst occupies a central place in this Review as a careful control of the metal particle size, particle dispersion on the support, the metastable phase formed under reaction conditions, its possible reconstruction, and faceting strongly influence the diameter of the carbon nanotubes, their structure (number of walls, graphene sheet orientation, chirality), their alignment, and the yield. The identified trends will be compared with recent observations on the growth of graphene. Recent results on metal-free catalysts will be analyzed from a different perspective. CNT Growth: the latest progress in carbon nanotube synthesis is reported and analyzed in this Review. We focus in particular on the dynamic nature of the metal active phase and its evolution when interacting with both the catalyst support or matrix, and the gas phase. A different light is shed on parameters crucial for large-scale production and for controlling their chirality. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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.

Wang D.,Xian Jiaotong University | Salje E.K.H.,University of Cambridge | Mi S.-B.,Xian 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.

Singh A.,Massachusetts Institute of Technology | Tao N.R.,Massachusetts Institute of Technology | Tao N.R.,CAS Shenyang Institute of Metal Research | Dao M.,Massachusetts Institute of Technology | Suresh S.,Massachusetts Institute of Technology
Scripta Materialia | Year: 2012

Bulk dynamic plastic deformation (DPD) materials comprise a composite structure of nanoscale twin bundles and nanoscale grains. The tribological properties of DPD-processed pure nano-Cu have been investigated in this study and compared with conventional coarse-grained (CG) Cu under both monotonic and repeated frictional sliding. We demonstrate that DPD nano-Cu and CG Cu exhibit steady-state mechanical characteristics after repeated frictional sliding that are similar to those seen in nanotwinned (NT) Cu produced by pulsed electrodeposition. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

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.

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.

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.

Grushko B.,Julich 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 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.

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 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.

Zhu Y.-J.,CAS Shenyang Institute of Metal Research
Yejin Fenxi/Metallurgical Analysis | Year: 2014

This paper provides an overview on the gas analysis in metals with reference to all the gas elements in the periodic table as well as carbon and sulfur. It's proposed that the conventional gas analysis has expanded from oxygen, nitrogen, hydrogen, carbon and sulfur to helium and argon. Gas analysis involves increasingly more types of materials, from metals and alloys to metallurgical furnace charges, metal oxides and ceramic materials, to name a few. The detection limit for gas analysis has been constantly renewed, toward both the lower and higher directions. New pulse heating-mass spectrometry have been applied to the gas analysis in metals and achieved simultaneous determination of four elements including oxygen, nitrogen, hydrogen and argon, so it is possible to boost changes in gas analysis. Spark source atomic emission spectrometer, X-ray fluorescence spectrometer and other non-special gas analysis instruments are also employed. For example, such means of microscopic analysis as secondary ion mass spectrometry (SIMS), ion probe (IM) and electron probe (EP) has been used as adjuncts in the gas analysis in metals, but they may grow into the major means as they develop.

Dai J.,Harbin Institute of Technology | Song Y.,Harbin Institute of Technology | Yang R.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2014

Influence of alloying elements (Ca, Mn, Ni, Cu, Zn, Zr, Sn, and La) and oxygen on stability and elastic properties of Mg17Al12 has been studied by first principles total energy calculations. The occupation preferences of oxygen and alloying elements in Mg17Al12 are identified. Ca, Zr, and La tend to substitute for Mg atoms, Zn, Cu, and Ni prefer to occupy Al site, and Mn and Sn show positive occupation energy for substituting both Mg and Al atoms. The impurity oxygen prefers to occupy interstitial sites surrounded by four Mg atoms regardless the presence of alloying elements in this system. Elastic constants were estimated to evaluate the mechanical stability of alloyed systems. The results show that alloys which own negative occupation energy also satisfy the mechanical stability criteria. Electronic structures were analyzed to clarify the intrinsic mechanisms of how alloying elements and oxygen influence the stability of Mg17Al 12. The stabilization effect of alloying elements and oxygen was found to originate from the strong bonding interaction with the matrix. © 2014 Elsevier B.V. All rights reserved.

Zou Y.,Ocean University of China | Wang J.,Ocean University of China | Wang J.,CAS Shenyang Institute of Metal Research | Zheng Y.Y.,Ocean University of China
Corrosion Science | Year: 2011

Corrosion rates of mild steel for long-term immersion were estimated by electrochemical and weight-loss methods. The results showed that application of electrochemical methods yielded erroneous values. The main reason was that, β-FeOOH, produced after long-term immersion with high electrochemical activity in the inner rust layer, exerted significant influence. In electrochemical tests, even small polarization can make β-FeOOH participate in cathodic reaction, which leads to overestimating corrosion rate. In order to confirm it, electrochemical behaviour was studied in aerated and deaerated conditions to investigate the effect of rust layers on reduction reaction. After calibration, the electrochemical measurement result was coincided with the weight loss. © 2010 Elsevier Ltd.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society
ChemSusChem | Year: 2014

What′s in store: The sustainable development of our society requires the conversion and storage of renewable energy, and these should be scaled up to serve the global primary energy consumption. This special issue on "The Chemistry of Energy Conversion and Storage", assembled by guest editor Dangsheng Su, contains papers dealing with these aspects, and highlights important developments in the chemistry of energy conversion and storage during the last two years. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang Z.H.,Harbin Institute of Technology | Zhang Z.H.,Xiamen University | Li M.Y.,Harbin Institute of Technology | Liu Z.Q.,Harbin Institute of Technology | And 2 more authors.
Acta Materialia | Year: 2016

This work investigated the growth characteristics and formation mechanisms of the Cu6Sn5 phase at the liquid-Sn0.7Cu/(111)Cu and liquid-Sn0.7Cu/(001)Cu joint interfaces. As a result of contributions from the interfacial environments, regular arrays of the roof-type Cu6Sn5 grains with fixed intersecting angles were generated on both types of the Cu single crystals after soldering at 250 °C for 1 s-1 h. At the liquid-Sn0.7Cu/Cu6Sn5 interface, a hexagonal-rod-type growth mechanism for Cu6Sn5 phase was proposed on the basis of its anisotropy in surface energy and roughness. According to this mechanism, the Cu6Sn5 roofs formed on the (111) and (001) Cu pads would consistently elongate in the [0001] direction of Cu6Sn5 phase, regardless of whether they belonged to the minimum mismatch direction of Cu6Sn5 and Cu phases; and they would maintain the {112¯0} and {101¯0} planes as the side faces respectively, despite the reaction time being prolonged to 1 h. At the Cu6Sn5/Cu interface, two types of the three-dimensional placement rules for Cu6Sn5 roofs on the Cu single crystals were determined on the basis of the suitable Cu matches of these two phases. Specifically, the junction interfaces between Cu6Sn5 roofs and Cu single crystals were confirmed to be ∥{101¯0} ∥ {111} and {112¯0} ∥ {001}; and the parallel orientation relationships of {0001} ∥ {011} were always present on both types of interfaces. Our study can help to clarify the growth mechanism of Cu6Sn5 phase and to provide a scientific basis of Cu6Sn5 orientation design for three-dimensional integrated circuit interconnect applications. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Feng A.H.,Harbin Institute of Technology | Chen D.L.,Ryerson University | Ma Z.Y.,CAS Shenyang Institute of Metal Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

Strain-controlled low-cycle fatigue (LCF) tests and microstructural evaluation were performed on a friction-stir-welded 6061Al-T651 alloy with varying welding parameters. Friction stir welding (FSW) resulted in fine recrystallized grains with uniformly distributed dispersoids and dissolution of primary strengthening precipitates β″ in the nugget zone (NZ). Two low-hardness zones (LHZs) appeared in the heat-affected zone (HAZ) adjacent to the border between the thermomechanically-affected zone (TMAZ) and HAZ, with the width decreasing with increasing welding speed. No obvious effect of the rotational rate on the LHZs was observed. Cyclic hardening of the friction-stir-welded joints was appreciably stronger than that of base metal (BM), and it also exhibited a two-stage character where cyclic hardening of the frictionstir-welded 6061Al-T651 alloy at higher strain amplitudes was initially stronger followed by an almost linear increase of cyclic stress amplitudes on the semilog scale. Fatigue life, cyclic yield strength, cyclic strain hardening exponent, and cyclic strength coefficient all increased with increasing welding speed, but were nearly independent of the rotational rate. Most friction-stirwelded joints failed along the LHZs and exhibited a shear fracture mode. Fatigue crack initiation was observed to occur from the specimen surface, and crack propagation was mainly characterized by the characteristic fatigue striations. Some distinctive tiremark patterns arising from the interaction between the hard dispersoids/inclusions and the relatively soft matrix in the LHZ under cyclic loading were observed to be present in-between the fatigue striations. © The Minerals, Metals & Materials Society and ASM International 2010.

Wang S.,CAS Shenyang Institute of Metal Research
Physical Chemistry Chemical Physics | Year: 2011

Information on orbital hybridization is very important to understand the structural, physical, and chemical properties of a material. Results of a comparative first-principles study on the behaviours of orbital hybridization in the two-dimensional single-element phases by carbon, silicon, and germanium are presented. From the well-known three-dimensional hexagonal lonsdaleite structure, in which the atoms are in ideal sp3-bonding, the layer spacing along c-axis is gradually stretched to simulate the evolutions of structural and electronic properties from three-dimensional to two-dimensional lattice configurations in the three materials. A turning point of the total system energy due to the sp3 to sp2 transition is observed during this process in carbon. In contrast, no such phenomenon is found in silicon and germanium. The differences in electronic structure and bonding behaviour are further examined through comparative investigation of atomic angular-momentum projected density of states and electronic energy band spectrums of these materials. We demonstrate that the valence electronic orbital in the two-dimensional hexagonal crystals of Si and Ge shows sp 3-like behaviour for the partial hybridization of s and p z, which leads to their different lattice configurations to graphene. The role of π-bonds in stabilizing the flat configuration of graphene is also discussed. © the Owner Societies 2011.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society
Angewandte Chemie - International Edition | Year: 2011

Two different methods recently yielded inorganic materials with double-helix structures: Silicon microtubes (see picture) formed when high inner pressure forced NaSi melt through an opening in the surface of a disc, and carbon nanotubes were prepared when plates of layered double hydroxide coated with active catalyst particles were used as substrate. These reports open the door for the application of double-helical inorganic materials in chemistry and biology. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Li X.,Shandong University of Technology | Xing W.,Shandong University of Technology | Zhuo S.,Shandong University of Technology | Zhou J.,Shandong University of Technology | And 3 more authors.
Bioresource Technology | Year: 2011

Series of nanoporous carbons are prepared from sunflower seed shell (SSS) by two different strategies and used as electrode material for electrochemical double-layer capacitor (EDLC). The surface area and pore-structure of the nanoporous carbons are characterized intensively using N2 adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature and dosage of KOH. Electrochemical measurements show that the carbons made by impregnation-activation process have better capacitive behavior and higher capacitance retention ratio at high drain current than the carbons made by carbonization-activation process, which is due to that there are abundant macroscopic pores and less interior micropore surface in the texture of the former. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons and commercial wood-based active carbon, thus highlighting the success of preparing high performance electrode material for EDLC from SSS. © 2010 Elsevier Ltd.

Xin G.,Dalian University of Technology | Yu B.,Dalian University of Technology | Xia Y.,Dalian University of Technology | Hu T.,Dalian University of Technology | And 2 more authors.
Journal of Physical Chemistry C | Year: 2014

Pt is one of the most effective cocatalysts used in hydrogen evolution. The efficient and optimum use of Pt is of great importance. In the present work, CdS loaded with Pt was synthesized via a coprecipitation method and annealing treatment, which exhibit remarkably higher efficiency for hydrogen evolution from water splitting compared with the traditional loading methods, i.e., photodeposition or impregnation under visible light. The effects of annealing temperature and different sacrificial reagents on H2 evolution have been systematically studied. The crystal phase, morphology, and optical and electrical properties of obtained catalysts were well-characterized by X-ray diffraction, transmission electron microscopy, UV-vis spectroscopy, and surface photovoltage tester, respectively. The valence state and loading amount of Pt were investigated by X-ray photoelectron spectroscopy and inductively coupled plasma. The enhanced photocatalytic activity of Pt/CdS by the coprecipitation method is mainly attributed to the intimate contact between Pt and CdS, as well as the efficient deoxidization of Pt4+ to Pt0 by annealing treatment. © 2014 American Chemical Society.

Li B.Q.,CAS Shenyang Institute of Metal Research | Sui M.L.,Beijing University of Technology | Mao S.X.,University of Pittsburgh
Applied Physics Letters | Year: 2010

It is usually believed that the partial dislocation and deformation twin are the results of permanent plasticity in materials. Here, we present in situ atomic-scale observation of reversible stacking fault and deformation twin during loading and unloading in nanocrystalline Ni under high-resolution transmission electron microscopy. The high propensity for the reversibility of the stacking fault and deformation twin is due to the high stacking fault force and small grain size, and will provide an understanding at atomistic scale on the nature of the deformation in nanocrystalline materials. © 2010 American Institute of Physics.

Hong S.,Hohai University | Wu Y.,Hohai University | Wang B.,Hohai University | Zheng Y.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Materials and Design | Year: 2014

In this paper, the Taguchi method was employed to optimize the spray parameters (spray distance, oxygen flow and kerosene flow) to achieve the highest hardness and, in turn, the best wear resistance of the high-velocity oxygen-fuel (HVOF) sprayed nanostructured WC-10Co-4Cr coating by investigating the correlation between the spray parameters and the hardness. The important sequence of spray parameters on the hardness of the coatings is kerosene flow>oxygen flow>spray distance, and the kerosene flow is the only significant factor. The optimal spray parameter (OSP) for the coating is obtained by optimizing hardness (330mm for the spray distance, 2000 scfh for the oxygen flow and 6.0 gph for the kerosene flow). The coating deposited under the OSP with low porosity and high microhardness consists predominately of WC and a certain amount of W2C phases. The coating deposited under the OSP exhibits better wear resistance compared with the cold work die steel Cr12MoV. The material removal of the coating is the extrusion of the ductile Co-Cr matrix followed by the crack and the removal of the hard WC particles. © 2013 Elsevier Ltd.

Zhang H.,Griffith University | Wang Y.,Griffith University | Liu P.,Griffith University | Han Y.,Griffith University | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2011

This work reports a facile hydrothermal approach to directly grow anatase TiO2 crystals with exposed {001} facets on titanium foil substrate by controlling pH of HF solution. The mechanistic role of HF for control growth of the crystal facet of anatase TiO2 crystals has been investigated. The results demonstrate that controlling solution pH controls the extent of surface fluorination of anatase TiO2, hence the size, shape, morphology, and {001} faceted surface area of TiO2 crystals. The theoretical calculations reveal that {001} faceted surface fluorination of anatase TiO2 can merely occur via dissociative adsorption of HF molecules under acidic conditions while the adsorption of Na+F - is thermodynamically prohibited. This confirms that the presence of molecular form of HF but not F- is essential for preservation of exposed {001} facets of anatase TiO2. Anatase TiO2 crystals with exposed {001} facets can be directly fabricated on titanium foil by controlling the solution pH 5.8. When pH is increased to near neutral and beyond (e.g., pH ≥ 6.6), the insufficient concentration of HF ([HF] 0.04%) dramatically reduces the extent of surface fluorination, leading to the formation of anatase TiO2 crystals with {101} facets and titanate nanorods/nanosheets. The anatase TiO2 nanocrystals with exposed {001} facets exhibits a superior photoelectrocatalytic activity toward water oxidation. The findings of this work clarify the mechanistic role of HF for controlling the crystal facet growth, providing a facile means for massive production of desired nanostructures with high reactive facets on solid substrates for other metal oxides. © 2011 American Chemical Society.

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 S.,CAS Shenyang Institute of Metal Research
AIP Advances | Year: 2013

Atomic structure models of six-component high-entropy alloys with body-centered cubic structure are successfully built according to the principle of maximum entropy for the first time. The lattice distortion parameters g of seven typical high-entropy alloys are calculated. From the optimized lattice configuration of high-entropy alloys, we show that these alloys are ideal three-dimensional paracrystals. The formation mechanism, structural feature, mechanical property, and application prospect of high-entropy alloys are discussed in comparison with the traditional alloys. The novel properties of body-centered cubic high-entropy alloys are attributed to the failure of dislocation deformation mechanism and the difficulty of directed particle diffusion. © 2013 © 2013 Author(s).

Wu L.-K.,Zhejiang University | Hu J.-M.,Zhejiang University | Zhang J.-Q.,Zhejiang University | Zhang J.-Q.,CAS Shenyang Institute of Metal Research
Journal of Materials Chemistry A | Year: 2013

A novel one-step sol-gel electrochemistry route to prepare superhydrophobic surfaces is presented. High roughness and low energy surfaces were obtained simultaneously during the formation of long-chain alkyl-grouped alkoxysilane films via electrochemically assisted deposition. Furthermore, significantly improved thermal and chemical stabilities and mechanical properties of the superhydrophobic surface were achieved by the incorporation of silica. © 2013 The Royal Society of Chemistry.

Fan X.-Y.,Tohoku University | Nouchi R.,Tohoku University | Yin L.-C.,CAS Shenyang Institute of Metal Research | Tanigaki K.,Tohoku University
Nanotechnology | Year: 2010

Because of the large reactivity of single layer graphene to electron-transfer chemistries, 4-nitrobenzene diazonium tetrafluoroborate is employed to modify the electrical properties of graphene field-effect transistors. After modification, the transfer characteristics of chemically modified graphene show a reduction in the minimum conductivity, electron-hole mobility asymmetry, a decrease in the electron/hole mobility, and a positive shift of the charge neutrality point with broadening of the minimum conductivity region. These phenomena are attributed to a dediazoniation reaction and the adsorbates on the graphene surface. © 2010 IOP Publishing Ltd Printed in the UK & the USA.

Guo J.,CAS Shenyang Institute of Metal Research
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2010

Some application basic theories related to the research and development of wrought superalloys and equiaxed grain cast superalloys were reviewed simply. The main contents are wrought superalloys and mechanisms of effect of minor elements; equiaxed crystal cast superalloys and creep mechanisms; and hot-corrosion resistant superalloys and discovery of new phase transformation as well as interaction effect of creep-fatigue-environment.

Yin L.-C.,Tohoku University | Yin L.-C.,CAS Shenyang Institute of Metal Research | Saito R.,Tohoku University | Dresselhaus M.S.,Massachusetts Institute of Technology
Nano Letters | Year: 2010

A metal-semiconductor transition in the smallest (2,2) single-wall carbon nanotube (SWNT) is predicted theoretically as a function of gate voltage. By hole-doping (or heavy electron-doping), the energy gap of a neutral (2,2) SWNT vanishes with structural change, and the (2,2) SWNT becomes metallic. The (2,2) tube assumes a doubly degenerate ground state around the charge neutral condition with an energy barrier, while this tube has only one nondegenerate metallic ground state over an energy window of -0.12 to +0.40 eV. Because of a high density of states at the Fermi energy for hole-doped (2,2) SWNTs, a possible superconducting transition is expected. © 2010 American Chemical Society.

Fang H.-T.,Harbin Institute of Technology | Liu M.,CAS Shenyang Institute of Metal Research | Wang D.-W.,University of Queensland | Ren X.-H.,Harbin Institute of Technology | Sun X.,Harbin Institute of Technology
Nano Energy | Year: 2013

A core-shell hybrid material of amorphous hydrous RuO2-coated carbon nanotubes (CNT-RuO2) with a RuO2 loading as high as 82.4wt% was prepared by a solution method using RuCl3 and NaHCO3 aqueous solutions. The effect of preparation conditions, especially the dripping speed of the NaHCO3 solution, on the formation of the core-shell structure was investigated, and the corresponding mechanism was discussed. Supercapacitive properties of the CNT-RuO2 and amorphous hydrous RuO2 electrodes with a thickness of over 200μm were studied and the crucial factors to govern their rate capability were analyzed. For the thick CNT-RuO2 electrode, a comparison of its specific capacitance before and after subtracting the effect of the voltage drop of discharge curves caused by the inner resistance of the CNT-RuO2 symmetrical supercapacitor indicates that electronic conductivity is more important than proton diffusion in determining its rate capability. © 2013 Elsevier Ltd.

Xiao W.,Wuhan University | Liu W.,Wuhan University | Mao X.,Wuhan University | Zhu H.,Wuhan University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

For the first time, a mesoporous hexagonal-phase Na0.17WO 3.085·0.29H2O nanosheet/microflower hierarchical structure has been synthesized employing a one-pot hydrothermal process with the assistance of Na2SO4. It is shown that Na 2SO4 not only acts as a stabilizer to facilitate the generation of a metastable hexagonal phase, but also function as a structure directing agent to assist the construction of nanosheet assemblies. The formation mechanisms have been rationalized. The materials have been thoroughly characterized by XRD/BET/FESEM/EDX/TEM/TGA. This hexagonal-phase Na 0.17WO3.085·0.29H2O nanosheet/ microflower hierarchical structure exhibits applicable electrochromic and adsorptive properties due to its unique crystallographic configuration and microstructures, promising its application in energy-saving smart windows and wastewater treatment. © The Royal Society of Chemistry 2013.

Rinaldi A.,Fritz Haber Institute of the Max Planck Society | Zhang J.,Fritz Haber Institute of the Max Planck Society | Zhang J.,CAS Shenyang Institute of Metal Research | Frank B.,Fritz Haber Institute of the Max Planck Society | And 3 more authors.
ChemSusChem | Year: 2010

Oxidative purification with mild diluted HNO3 followed by NaOH washing lowers the amount of amorphous carbon attached to multiwalled carbon nanotubes (CNTs). The graphitic structure improves remarkably by further annealing in argon at elevated temperatures, that is, 1173, 1573, and 1973 K. The influence of the purification treatment on the catalytic activity of the CNTs is investigated for the oxidative dehydrogenation (ODH) of ethylbenzene and propane as probe reactions. All samples tend to approach an appropriately ordered structure and Raman analysis of the used samples displays a D/G band ratio of 0.95-1.42. Oxygen functionalities are partly removed by the annealing treatment and can be rebuilt to some extent by oxygen molecules in the ODH reactant flow. The presence of amorphous carbon is detrimental to the catalytic performance as it allows for unwanted functional groups occurring in parallel with the formation of the selective (di)ketonic active sites. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Sun X.,University of California at Santa Barbara | Li B.,CAS Shenyang Institute of Metal Research | Metiu H.,University of California at Santa Barbara
Journal of Physical Chemistry C | Year: 2013

We report the results of density-functional theory calculations for the dissociative adsorption of methane (DAM) on CaO(001) doped with Li, Na, K, and Cu. The presence of these dopants lowers the energy of oxygen-vacancy formation, increases the energy of the DAM reaction, and lowers the activation energy for DAM. We performed the same calculations for a stepped CaO(001) surface doped with Na and found that Na prefers being located at a step and the activation energy for DAM is lower at this step than on the doped, flat surface. We propose that such trends are valid for all oxides doped with lower-valence dopants. © 2013 American Chemical Society.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society
Angewandte Chemie - International Edition | Year: 2010

Time and motion studies: 4D electron tomography enables the direct investigation of transient states of materials, structural dynamics of large molecular objects (for example the motion of a spiral carbon nanotube), and biological systems under controlled conditions. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wei L.,Xiamen University | Zhou Z.-Y.,Xiamen University | Chen S.-P.,Xiamen University | Xu C.-D.,Xiamen University | And 4 more authors.
Chemical Communications | Year: 2013

Pt triambic icosahedral nanocrystals (TIH NCs) enclosed by {771} high-index facets were successfully synthesized electrochemically, for the first time, in ChCl-urea based deep eutectic solvents, and exhibited higher electrocatalytic activity and stability towards ethanol electrooxidation than a commercial Pt black catalyst. © 2013 The Royal Society of Chemistry.

Wang X.-M.,Zhejiang University | Hu J.-M.,Zhejiang University | Zhang J.-Q.,Zhejiang University | Zhang J.-Q.,CAS Shenyang Institute of Metal Research
Electrochimica Acta | Year: 2010

Mixed IrO2-SiO2 oxide films were prepared on titanium substrate by the thermo-decomposition of hexachloroiridate (H2IrCl6) and tetraethoxysilane (TEOS) mixed precursors in organic solvents. The solution chemistry and thermal decomposition kinetics of the mixed precursors were investigated by ultra violet/visible (UV/vis) spectroscopy and thermogravimetry (TGA) and differential thermal analysis (DTA), respectively. The physiochemical characterization of the resulting materials was conducted by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. It is shown from the UV/vis spectra that the electronic absorption intensity of IrCl6 2- complexes in the precursors decreases in the presence of TEOS, indicating the interaction between these two components. Thermal analysis shows the decomposition reaction of H2IrCl6 is inhibited by TEOS in the low temperature range, but the further oxidation reaction at high temperatures of formed intermediates is independent of the presence of silane component. Physical measurements show a restriction effect of silica on the crystallization and crystal growth processes of IrO2, leading to the formation of finer oxide particles and the porous morphology of the binary oxide films. The porous composite films exhibit high apparent electrocatalytic activity toward the oxygen evolution reaction. In addition, the long-term stability of Ti-supported IrO2 electrodes is found to apparently improve with appropriate amount of SiO2 incorporation, as tested under galvanostatic electrolysis. © 2010 Elsevier Ltd. All rights reserved.

Yang X.H.,East China University of Science and Technology | Li Z.,University of Queensland | Liu G.,CAS Shenyang Institute of Metal Research | Xing J.,East China University of Science and Technology | And 3 more authors.
CrystEngComm | Year: 2011

Ultra-thin anatase TiO2 nanosheets with dominant {001} facets (∼82%) and controllable thickness (1.6-2.7 nm) were synthesized by using a modified one-pot hydrothermal route. As a morphology controlling agent, the concentration of hydrofluoric acid has a significant impact on the thickness of the as-synthesized TiO2 nanosheets. In addition, according to the XRD patterns and TEM images of the products on different reaction stages, the growth process of TiO2 nanosheets was clarified for the first time. We further measured the efficiency for H2 evolution of the ultra-thin anatase TiO2 nanosheets loaded with 1 wt% Pt from photochemical reduction of water in the presence of methanol as a scavenger. The TiO 2 nanosheets exhibited a H2 evolution rate as high as 7381 μmol h-1 g-1 under UV-vis light irradiation, attributing to their exposed reactive {001} facets and high crystallinity. © 2011 The Royal Society of Chemistry.

Li J.,University of California at Berkeley | Tan A.,University of California at Berkeley | Ma S.,University of California at Berkeley | Ma S.,CAS Shenyang Institute of Metal Research | And 4 more authors.
Physical Review Letters | Year: 2014

Fe/NiO/Fe/CoO/Ag(001) single crystalline films were grown epitaxially and investigated by x-ray magnetic circular dichroism and x-ray magnetic linear dichroism. The bottom Fe layer magnetization is pinned through exchange coupling to the CoO layer and the top Fe layer magnetization can be rotated by an in-plane external magnetic field. We find that the NiO spins wind up to form a domain wall due to the perpendicular NiO/Fe interfacial coupling as the top layer Fe magnetization rotates from 0° to 90°, but switch wall chirality and unwind the wall as the Fe magnetization rotates from 90° to 180°. This observation shows that Mauri's 180° domain wall does not exist in perpendicularly coupled ferromagnetic-antiferromagnetic systems in the strong coupling regime. © 2014 American Physical Society.

Zhang Y.,Ningbo Institute of Materials Technology and Engineering | Zhang J.,Ningbo Institute of Materials Technology and Engineering | Su D.S.,CAS Shenyang Institute of Metal Research
ChemSusChem | Year: 2014

The electronic properties of carbon nanotubes (CNTs) can be tuned by substitutional doping with heteroatoms (mainly B and N) to expand the applications of CNTs. Based on the comprehensive understanding of the substitutional doping of CNTs, it should be possible to deliberately design doped CNTs for specific purposes. Thus, relevant experimental and theoretical works are reviewed herein in an attempt to correlate the synthetic methods, electronic properties, and applications of heteroatom-doped CNTs. The distribution and arrangement of heteroatoms in the graphitic lattice of CNTs can be modulated through the choice of synthetic conditions, which would further lead to different electronic properties of CNTs for their chemical applications. Hit the target! The electronic properties of carbon nanotubes (CNTs) can be tuned by substitutional doping with heteroatoms (B and/or N) for different applications. Based on the comprehensive understanding of the substitutional doping of CNTs, it should be possible to deliberately design doped CNTs for specific purposes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gao Y.,CAS Dalian Institute of Chemical Physics | Ma D.,CAS Beijing National Laboratory for Molecular | Hu G.,Exponent, Inc. | Zhai P.,CAS Beijing National Laboratory for Molecular | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2011

Into the layer: Layered carbon-iron oxide nano-composites catalysts are very active in catalytic oxidation reactions. The size and structure of the iron oxide nanoparticles (blue in the TEM image) embedded in the layered carbon can be controlled very simply by changing the temperature of the synthesis reaction. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Titirici M.-M.,Queen Mary, University of London | White R.J.,Institute for Advanced Sustainability Studies | Brun N.,Charles Gerhardt Institute | Budarin V.L.,University of York | And 4 more authors.
Chemical Society Reviews | Year: 2015

Carbon-based structures are the most versatile materials used in the modern field of renewable energy (i.e., in both generation and storage) and environmental science (e.g., purification/remediation). However, there is a need and indeed a desire to develop increasingly more sustainable variants of classical carbon materials (e.g., activated carbons, carbon nanotubes, carbon aerogels, etc.), particularly when the whole life cycle is considered (i.e., from precursor "cradle" to "green" manufacturing and the product end-of-life "grave"). In this regard, and perhaps mimicking in some respects the natural carbon cycles/production, utilization of natural, abundant and more renewable precursors, coupled with simpler, lower energy synthetic processes which can contribute in part to the reduction in greenhouse gas emissions or the use of toxic elements, can be considered as crucial parameters in the development of sustainable materials manufacturing. Therefore, the synthesis and application of sustainable carbon materials are receiving increasing levels of interest, particularly as application benefits in the context of future energy/chemical industry are becoming recognized. This review will introduce to the reader the most recent and important progress regarding the production of sustainable carbon materials, whilst also highlighting their application in important environmental and energy related fields. © The Royal Society of Chemistry 2015.

Liu X.,Fritz Haber Institute of the Max Planck Society | Frank B.,Fritz Haber Institute of the Max Planck Society | Zhang W.,Fritz Haber Institute of the Max Planck Society | Cotter T.P.,Fritz Haber Institute of the Max Planck Society | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2011

Onions are a girl's best friend: While catalyzing the oxidative dehydrogenation of n-butane, ultradispersed nanodiamonds (UDD) are transformed into onionlike carbon (OLC, see picture). This surface-activated bulk transformation from sp3-to sp2-hybridized carbon atoms is concomitant with an enhanced product selectivity to the desired butenes. In addition, the synthesis of OLC is achieved at temperatures 600-K lower than reported so far. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society | Sun G.,CAS Dalian Institute of Chemical Physics
Angewandte Chemie - International Edition | Year: 2011

Within reach: Newly developed nonprecious-metal catalysts can be used to produce inexpensive hydrogen fuel cells with performances approaching those of platinum-based systems. For example, the best non-Pt catalyst was prepared from a metal-organic framework consisting of zeolitic Zn II imidazolate which served as the host for the Fe and N precursors of the catalyst. The plot shows the volumetric current densities of the best non-Pt catalysts and the target value set by the U.S. DOE at 0.8 V). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cui Y.,CAS Changchun Institute of Applied Chemistry | Cui Y.,CAS Shenyang Institute of Metal Research | Wang G.,CAS Changchun Institute of Applied Chemistry | Pan D.,CAS Changchun Institute of Applied Chemistry
CrystEngComm | Year: 2013

Metastable wurtzite I3-III-IV-VI5 (Cu 3InSnS5) semiconductor nanocrystals were successfully synthesized via a hot-injection approach. The structure, composition, morphology, and optical properties of Cu3InSnS5 were characterized by powder X-ray diffraction, energy dispersive spectrometry, transmission electron microscopy, and UV-Vis absorption. Their suitable band gap value and photoresponse indicate a high potential application in the field of thin film solar cells. © 2013 The Royal Society of Chemistry.

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.

Liu Q.,Kyushu University | Fujigaya T.,Kyushu University | Cheng H.-M.,Japan Science and Technology Agency | Nakashima N.,Kyushu University | Nakashima N.,CAS Shenyang Institute of Metal Research
Journal of the American Chemical Society | Year: 2010

Transparent and conductive single-walled carbon nanotube (SWNT) films are of great importance to a number of applications such as optical and electronic devices. Here, we describe a simple approach for preparing free-standing highly conductive transparent SWNT films with a 20-150 nm thickness by spray coating from surfactant-dispersed aqueous solutions of SWNTs synthesized by an improved floating-catalyst growth method. After the HNO3 treatment, dipping the SWNT films supporting on glass substrates in water resulted in a quick and nondestructive self-release to form free-standing ultrathin SWNT films on the water surface. The obtained films have sufficiently high transmittance (i.e., 95%), a very low sheet resistance (i.e., ∼120 δ/sq), and a small average surface roughness (i.e., ∼3.5 nm for a displayed 10×10 μm area). Furthermore, the floating SWNT films on the water surface were easily transferred to any substrates of interest, without intense mechanical and chemical treatments, to preserve their original sizes and network structures. For example, the transferred SWNT films on poly(ethylene terephthalate) films are mechanically flexible, which is a great advantage over conventional indium-tin oxide (ITO) and therefore strongly promise to be "post ITO" for many applications. © 2010 American Chemical Society.

Xu C.,CAS Shenyang Institute of Metal Research
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 ∼10 μm. 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 Nature Publishing Group

Sun J.,Northeastern University China | Tong W.P.,Northeastern University China | Zuo L.,Northeastern University China | Wang Z.B.,CAS Shenyang Institute of Metal Research
Materials and Design | Year: 2013

A nanostructured surface layer was fabricated on titanium layer of a Ti/Al clad sheet composite by means of the surface mechanical attrition treatment (SMAT). The low-temperature plasma nitriding treatment of the SMAT sample was investigated in comparison with the coarse-grained sample by using structural analysis (X-ray diffraction, scanning electron microscopy, and transmission electron microscopy) as well as mechanical and corrosion property measurements. Results showed that the nitriding kinetics of the SMAT sample with the nanostructured surface layer was greatly enhanced, so that the nitriding temperature could be as low as 550°C, which is significantly lower than the melting point of the aluminum layer on Ti/Al clad sheet (conventional nitriding can lead to melting of the aluminum layer due to higher temperature about 800°C). The nitrided layer of the SMAT sample was composed of nanostructured ε-TiN and γ-Ti2N phase with high supersaturation of nitrogen. The surface hardness and the hardened surface layer thickness as well as the wear and corrosion resistances of the nitrided SMAT sample were all substantially enhanced relative to the nitrided coarse-grained sample. © 2012 Elsevier Ltd.

Shao C.W.,Northeastern University China | Shao C.W.,CAS Shenyang Institute of Metal Research | Shi F.,Northeastern University China | Li X.W.,Northeastern University China
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2015

Cyclic deformation and damage behavior of a Ni-free high-nitrogen austenitic stainless steel with a composition of Fe-18Cr-18Mn-0.63N (weight pct) were studied, and the internal stress and effective stress were estimated by partitioning the hysteresis loop during cyclic straining at total strain amplitudes ranging from 3.0 × 10−3 to 1.0 × 10−2. It is found that immediate cyclic softening takes place at all strain amplitudes and subsequently a saturation or quasi-saturation state develops and occupies the main part of the whole fatigue life. The internal stress increases with increasing strain amplitude, while the variation of effective stress with strain amplitude is somewhat complicated. Such a phenomenon is discussed in terms of dislocation structures and the short-range ordering caused by the interaction between nitrogen atoms and substitutional atoms. The relationship of fatigue life vs plastic strain amplitude (Nf−Δεpl/2) follows a bilinear Coffin–Manson rule, resulting from the variation in slip deformation mode with the applied strain amplitude. At the low strain amplitude, cracks initiate along slip bands, and planar slip dislocation configurations dominate the major characteristic of internal microstructures. At high strain amplitudes, intergranular (mostly along grain boundaries and few along twin boundaries) cracks are generally found, and the deformation microstructures are mainly composed of dislocation cells, stacking faults and a small amount of deformation twins, in addition to planar slip dislocation structures. © 2015, The Minerals, Metals & Materials Society and ASM International.

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.

Song Y.,Harbin Institute of Technology | Dai J.H.,Harbin Institute of Technology | Yang R.,CAS Shenyang Institute of Metal Research
Surface Science | Year: 2012

We studied the adsorption behavior of oxygen on low index surfaces of γ-TiAl via first principles to investigate the mechanism that drives the adsorption behavior. The (100) surface is the most stable surface energetically followed by the (111), (110) and (001) surfaces. A study of the adsorption of a single oxygen atom on surfaces of TiAl showed that the O atom prefers the Ti-rich environment that has a high potential of generating TiO 2. Competition between O-Al bonding and O-Ti bonding was observed in the O adsorbed surface regions. However, the O-Ti interaction dominates the adsorption behavior in all considered systems except when O is adsorbed on an Al-terminated (001) surface as the O-Al bond is stronger than O-Ti bond. A linear relationship between adsorption energy and integration of orbital overlaps between the O atom and the metals is obtained, which indicates that the electronic structure controls the adsorption behavior of an O atom on a γ-TiAl surface - an opportunity to improve the oxidation resistance of γ-TiAl based alloys. © 2012 Elsevier B.V. All rights reserved.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society | Perathoner S.,Messina University | Centi G.,Messina University
Chemical Reviews | Year: 2013

Nanocarbon is a term increasingly used to indicate the broad range of carbon materials having a tailored nanoscale dimension and functional properties that significantly depend on their nanoscale features. CNT and graphene belong to this class of materials comprising many more types of carbon materials, such as nanofibers, -coils, -diamonds, -horns, -onions, and fullerene. The field of application of nanocarbon materials is large, because they possess electrical and thermal conductivity, as well as a mechanical strength and lightness that conventional materials cannot match. With the diversity of their structure, these characteristic values can be achieved over an extremely wide range of conditions. For these reasons, they are extensively studied in applications going from photonics and optoelectronics to biotech and nanomedicine, advanced electrodes, and polymer composites. It should be mentioned that for commercial applications a comprehensive understanding of the catalyst structure, bonding, and properties is desirable, but not strictly necessary, provided that the catalysts are well-reproducible and give superior performances.

Frank B.,Fritz Haber Institute of the Max Planck Society | Schuster M.E.,Fritz Haber Institute of the Max Planck Society | Schlogl R.,Fritz Haber Institute of the Max Planck Society | Su D.S.,Fritz Haber Institute of the Max Planck Society | Su D.S.,CAS Shenyang Institute of Metal Research
Angewandte Chemie - International Edition | Year: 2013

Soot toxification: The increasing chemical activity of the emitted soot particulate produced by modern diesel engines is an unwanted side effect of modification of the motors. This makes Euro IV and VI soots chemically and biologically highly active and hazardous. Taking these factors into consideration, the question arises whether the reduced net mass of diesel soot particulate emitted overcompensates for the induced micro- and nanostructure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Su D.S.,CAS Shenyang Institute of Metal Research | Centi G.,Messina University
Journal of Energy Chemistry | Year: 2013

Nanocarbon materials play a critical role in the development of new or improved technologies and devices for sustainable production and use of renewable energy. This perspective paper defines some of the trends and outlooks in this exciting area, with the effort of evidencing some of the possibilities offered from the growing level of knowledge, as testified from the exponentially rising number of publications, and putting bases for a more rational design of these nanomaterials. The basic members of the new carbon family are fullerene, graphene, and carbon nanotube. Derived from them are carbon quantum dots, nanohorn, nanofiber, nano ribbon, nanocapsulate, nanocage and other nanomorphologies. Second generation nanocarbons are those which have been modified by surface functionalization or doping with heteroatoms to create specific tailored properties. The third generation of nanocarbons is the nanoarchitectured supramolecular hybrids or composites of the first and second generation nanocarbons, or with organic or inorganic species. The advantages of the new carbon materials, relating to the field of sustainable energy, are discussed, evidencing the unique properties that they offer for developing next generation solar devices and energy storage solutions. Copyright © 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

Xu F.,Sun Yat Sen University | Cai R.,Sun Yat Sen University | Zeng Q.,Sun Yat Sen University | Zou C.,Sun Yat Sen University | And 5 more authors.
Journal of Materials Chemistry | Year: 2011

In this paper, we report the electrochemical capacitive properties of polystyrene-based hierarchical porous carbon (PS-HPC) for supercapacitors. Compared to many porous carbons such as a commercially available activated carbon and an ordered mesoporous carbon, PS-HPC has a unique three-dimensionally (3D) interconnected micro-, meso- and macroporous network and thus exhibits faster ion transport behavior and a larger utilization of surface area in electric double layer capacitors. The 3D interconnected meso- and macroporous network originates respectively from the compact and loose aggregation of crosslinked polystyrene-based carbon nanoparticles, and is able to facilitate rapid ion transfer/diffusion rates. Furthermore, PS-HPC's micropores exist from the 3D interconnected network inside these crosslinked polystyrene-based carbon nanoparticles, thus giving an exceptional electrochemically accessible surface area for charge accumulation. As a result, the capacitance retention ratio and capacitance per surface area of PS-HPC at a high sweep rate of 200 mV s -1 are as high as 84% and 28.7 μF cm-2, respectively. These encouraging results demonstrate the promising application of PS-HPC for high performance supercapacitors. © 2011 The Royal Society of Chemistry.

Gao Y.,CAS Beijing National Laboratory for Molecular | Gao Y.,CAS Dalian Institute of Chemical Physics | Hu G.,CAS Beijing National Laboratory for Molecular | Zhong J.,Soochow University of China | And 6 more authors.
Angewandte Chemie - International Edition | Year: 2013

Thanks to nitrogen introduced into the layered carbon framework of graphite, the chemical reactivity of the carbon atoms was increased. N-doped graphitic catalysts generate reactive oxygen species and display excellent activity for hydrocarbon activation even at room temperature. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Huang C.-H.,National Tsing Hua University | Huang C.-H.,Fritz Haber Institute of the Max Planck Society | Zhang Q.,Fritz Haber Institute of the Max Planck Society | Zhang Q.,Tsinghua University | And 6 more authors.
ChemSusChem | Year: 2012

Three-dimensional, hierarchically ordered, porous carbon (HOPC) with designed porous textures, serving as an ion-buffering reservoir, an ion-transport channel, and a charge-storage material, is expected to be advanced an energy material for high-rate supercapacitors. Herein, HOPC without/with partially graphitic nanostructures have been directly synthesized by means of a simple one-pot synthesis procedure. The designed porous textures of the 3D HOPC materials are composed of highly ordered, fcc macroporous (300 nm), interconnected porous structures, including macroporous windows (170 nm), hexagonally ordered mesopores (5.0 nm), and useful micropores (1.2 nm). 3D HOPC-g-1000 (g=graphitic, 1000=pyrolysis temperature of 1000 °C) with partially graphitic nanostructures has a low specific surface area (296 m 2 g -1) and a low gravimetric specific capacitance (73.4 F g -1 at 3 mV s -1), but improved electrical conductivity, better rate performance, higher electrolyte accessibility (24.8 μF cm -2 at 3 mV s -1), faster frequency response (≈1 Hz), and excellent cycling performance (>5400 cycles). The specific capacitance per surface area is higher than that of conventional porous carbons, carbon nanotubes, and modified graphene (10-19 μF cm -2). Open up! A three-dimensional hierarchically-ordered porous carbon with partially graphitic nanostructure has been designed, fabricated, and explored as a supercapacitor electrode (see picture). The macropores, interconnected porous structures, and meso/micropores are used as ion-buffering reservoirs, ion-transport channels, and charge-storage materials, respectively, and are expected to be advanced energy materials for high-rate supercapacitors. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li M.C.,Dalian University of Technology | Hao S.Z.,Dalian University of Technology | Wen H.,Huazhong University of Science and Technology | Huang R.F.,CAS Shenyang Institute of Metal Research
Applied Surface Science | Year: 2014

High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm2 and pulse duration 2.5 μs. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic α phase and Mg 17Al12 particles started to dissolve in the surface modified layer of depth ∼15 μm. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg 3.1Al0.9 domains surrounded by network of Mg 17Al12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy. © 2014 Elsevier B.V.

Geng S.,Northeastern University China | Li Y.,Northeastern University China | Ma Z.,Northeastern University China | Wang L.,Northeastern University China | And 2 more authors.
Journal of Power Sources | Year: 2010

Fe-Ni alloy is electrodeposited on ferritic stainless steel for intermediate-temperature solid oxide fuel cell (SOFC) interconnects application. The oxidation behavior of Fe-Ni alloy coated steel has been investigated at 800 °C in air corresponding to the cathode environment of SOFC. It is found that the oxidation rate of the Fe-Ni alloy coated steel becomes similar to that of the uncoated steel after the first week thermal exposure, although the mass gain of the coated steel is higher than that of the uncoated steel. Oxide scale formed on the uncoated steel mainly consists of Cr2O3 with (Mn,Cr)3O4 spinel. However, a double-layer oxide structure with a Cr-free outer layer of Fe2O3/NiFe2O4 and an inner layer of Cr2O3 is developed on the Fe-Ni alloy coated steel. The scale area specific resistance (ASR) for the Fe-Ni alloy coated steel is lower than that of the scale for the uncoated steel. © 2009 Elsevier B.V. All rights reserved.

Dai J.H.,Harbin Institute of Technology | Song Y.,Harbin Institute of Technology | Yang R.,CAS Shenyang Institute of Metal Research
Journal of Physical Chemistry C | Year: 2010

First principles calculations on an Al, Ti, Mn, and Ni doped MgH 2 (110) surface were carried out to study the influence of dopants on the dehydrogenation properties of MgH2. It was shown that Al prefers to substitute for an Mg atom, whereas Ti, Mn, and Ni prefer to occupy interstitial sites. The dopants used different mechanisms to improve the dehydrogenation properties of MgH2. Al weakens the interactions between the Mg and the H atoms in its vicinity and so slightly improved the dehydrogenation properties of the Al doped system. The H atoms near the dopants of the transition metal doped systems were dramatically distorted. Ti has a high potential to generate a TiH2 phase by attracting two H atoms, which frees one H atom from its host Mg atom. The dehydrogenation properties of the Mn doped system were improved by the formation of a Mn-H cluster with a similar structure to Mg3MnH7 but weaker interactions between its atoms. If the MgH2 (110) surface is doped with Ni, the Ni will attract four H atoms to form a regular tetrahedral NiH4 group almost identical in structure to that in Mg2NiH4. The improvement of the dehydrogenation properties of Ni-doped MgH2 is expected as the bonding between the Mg and the H atoms is weakened, and there is a high possibility that the Mg2NiH4 phase will be formed, which is thermodynamically less stable than the MgH2 in this system. © 2010 American Chemical Society.

Yang R.,CAS Shenyang Institute of Metal Research
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2015

The history of research and development of γ-TiAl intermetallic alloys was outlined and divided into 4 stages: starting (1974~1985), revolutionary (1986~1995), emerging (1996~2005) and specialty materials (2006~). Major events and landmarks at the different stages were recounted to provide a framework for understanding scientific and technological progress. Key advances in the following 6 areas were reviewed: alloying, microstructure type, primary processing (melting), secondary processing (hot working), properties (including creep, fracture and fatigue, and oxidation), and tertiary processing (forming, covering both investment casting and near- net shape powder metallurgy). Future challenges were identified as follows: improvement of centrifugal casting technology, low-cost wrought process, development of third-generation alloys that meet design specifications, new applications based on new technologies, and viability of new forming routes such as additive manufacturing. © Copyright.

Luo B.,University of Queensland | Liu G.,CAS Shenyang Institute of Metal Research | Wang L.,University of Queensland
Nanoscale | Year: 2016

Two-dimensional (2D) materials have attracted increasing attention for photocatalytic applications because of their unique thickness dependent physical and chemical properties. This review gives a brief overview of the recent developments concerning the chemical synthesis and structural design of 2D materials at the nanoscale and their applications in photocatalytic areas. In particular, recent progress on the emerging strategies for tailoring 2D material-based photocatalysts to improve their photo-activity including elemental doping, heterostructure design and functional architecture assembly is discussed. © The Royal Society of Chemistry 2016.

Liu G.,University of Science and Technology Beijing | Xu J.,CAS Shenyang Institute of Metal Research | Wang Y.,University of Science and Technology Beijing | Wang X.,University of Science and Technology Beijing
Journal of Materials Chemistry A | Year: 2015

Developing catalysts with high electrocatalytic activity has recently attracted much attention due to the slow reaction kinetics for oxygen evolution reaction (OER) and poor durability under harsh operating environments. Aiming at the enhancement of oxygen electrode kinetics and durability, a facile and scalable electrospinning method is employed to fabricate antimony doped tin oxide nanowires (Sb-SnO2 NWs) as support materials for iridium oxide. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that the as-prepared Sb-SnO2 NW is stacked from primary Sb-SnO2 nanoparticles (Sb-SnO2 NPs) with diameters of 15-25 nm and exhibits a uniform porous nanowire structure with diameters in the range of 200-300 nm. The synthesized Sb-SnO2 NW has a BET surface area of 60 m2 g-1 and an electronic conductivity of 0.83 S cm-1. Benefiting from the porous nanowire structure and high electronic conductivity of the Sb-SnO2 NW support, the supported IrO2 catalyst exhibits significant enhancement of mass activity toward OER in acidic electrolytes compared with that of Sb-SnO2 NP supported IrO2 catalyst and pure IrO2. The improved catalytic performance for OER is further confirmed by proton exchange membrane (PEM) electrolyzer tests at 80 °C. A test of such an electrolyzer cell at 450 mA cm-2 shows good durability within a period of up to 646 h. © The Royal Society of Chemistry 2015.

Chen Z.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Liang Z.,CAS Shenyang Institute of Metal Research
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

In recent experiments, spin-orbit-coupled (SOC) bosonic gases in an optical lattice have been successfully prepared into any Bloch band [Hamner, Phys. Rev. Lett. 114, 070401 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.070401], which promises a viable contender in the competitive field of simulating gauge-related phenomena. However, the ground-state phase diagram of such systems in the superfluid regime is still lacking. Here we present a detailed study of the phase diagram in an optically trapped Bose gas with equal-weight Rashba and Dresselhaus SO coupling. We identify four different quantum phases, which include three normal phases and a mixed phase, by considering the wave vector k1, the longitudinal (σz), and the transverse (σx) spin polarizations as three order parameters. The ground state of normal phases is a Bloch wave with a single wave vector k1, which can position in arbitrary regions in the Brillouin zone. By contrast, the ground state of the mixed phase is a superposition of two Bloch waves with opposite k1, which, remarkably, may lack periodicity even though the system's Hamiltonian is periodic. This mixed phase in the lattice setting can be seen as the counterpart of the stripe phase associated with the uniform SOC gas. Furthermore, due to the lattice-renormalized SOC, the phase diagram of the model system becomes significantly different from the uniform case when the lattice strength grows. Finally, a scheme for experimentally probing the mixed phase using Bragg spectroscopy is proposed. © 2016 American Physical Society.

Dai J.H.,Harbin Institute of Technology | Song Y.,Harbin Institute of Technology | Yang R.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2011

A first principle study was carried out to investigate the dehydrogenation properties of metal (001) surface doped MgH2. Site preference of dopants was identified and dehydrogenation properties of the doped systems were analyzed based on the total energy and electronic structure calculations. It was shown that Al and Ti prefer to substitute for Mg atoms, whereas Mn and Ni prefer to occupy interstitial sites. The mechanisms that dopants improve the dehydrogenation properties of the considered systems were clarified. Al weakens the interactions between the Mg and the H atoms and has high potential to drive a formation of an Al-Mg cluster, and therefore improves the dehydrogenation performance of the Al doped system. Ti strongly interacts with its neighboring H atoms, distorts their positions, and could potentially generate a TiH 2 phase by attracting two H atoms. Mn greatly distorts the surface structure and causes a dramatic reduction on the dehydrogenation energy in the Mn interstitially doped system. A Ni-H tetrahedral cluster is observed, which acts as a seed to form Mg2NiH4 phase, in the Ni doped MgH2 (001) surface. Therefore, the improvement of the dehydrogenation properties of Ni doped system is expectable due to the formation of thermodynamically less stable Mg2NiH4 phase. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Du X.,Shenyang Ligong University | Wu E.,CAS Shenyang Institute of Metal Research
Surface and Interface Analysis | Year: 2013

The adsorption isotherms of hydrogen on microporous zeolite ZSM-5, at supercritical conditions, have been modeled using the monolayer lattice density functional theory (LDFT) models, where the simple cubic lattice, face-centered cubic lattice, body-centered cubic lattice and tetragonal lattice structures are assumed for the arrangements of the adsorption sites inside pores based on the size and shape of the zeolite. The results indicate that the monolayer LDFT models appear to be effective in describing hydrogen adsorption on zeolite ZSM-5 at supercritical conditions, and the calculated adsorption isotherms agree well with the experimental isotherms measured previously. The layer density of adsorbed phase is presented versus the bulk density and temperature. It is found that the densities of adsorbed phase on adsorbent surface are much higher than the bulk density for temperature range under study. However, in the core region, the layer densities are close to the bulk density. The monolayer adsorption is suitable for hydrogen on ZSM-5 zeolite. Copyright © 2013 John Wiley & Sons, Ltd.

Chen H.,Harbin Institute of Technology | Zhang E.,Northeastern University China | Yang K.,CAS Shenyang Institute of Metal Research
Materials Science and Engineering C | Year: 2014

In order to improve the biocompatibility and the corrosion resistance in the initial stage of implantation, a phosphate (CaZn2(PO 4)2 · 2H2O) coating was obtained on the surface of pure iron by a chemical reaction method. The anti-corrosion property, the blood compatibility and the cell toxicity of the coated pure iron specimens were investigated. The coating was composed of some fine phosphate crystals and the surface of coating was flat and dense enough. The electrochemical data indicated that the corrosion resistance of the coated pure iron was improved with the increase of phosphating time. When the specimen was phosphated for 30 min, the corrosion resistance (Rp) increased to 8006 Ω. Compared with that of the naked pure iron, the anti-hemolysis property and cell compatibility of the coated specimen was improved significantly, while the anti-coagulant property became slightly worse due to the existence of element calcium. It was thought that phosphating treatment might be an effective method to improve the biocompatibility of pure iron for biomedical application. © 2013 Elsevier B.V.

Liu Y.,CAS Shenyang Institute of Metal Research | Chao D.,Jilin University | Yao H.,Jilin University
Organic Electronics: physics, materials, applications | Year: 2014

A new carbazole-derived triphenylamine-containing diimide-diacid monomer (5), 4,4′-bis(trimellitimido)-4″-N-carbazolytriphenylamine, is prepared by the condensation of 4,4′-diamino-4″-N- carbazolytriphenylamine (4) and two molar equivalents of trimellitic anhydride (TMA). A series of new poly(amide-imide)s (PAIs) 7a-7d with carbazole- substituted triphenylamine units are prepared by direct polymerization from the new diimide-diacid (5) and various aromatic diamines (6a-6d). The PAIs shows high glass transition temperature between 269 and 297 °C, and high 5% weight loss temperature between 526 and 561 °C under nitrogen environment. Cyclic voltammograms of the PAIs films, which are casted onto the indium-tin oxide (ITO)-coated glass substrate, exhibit two reversible oxidation redox couples at 1.05-1.08 V and 1.38-1.46 V under an anodic sweep. The PAI-7a film reveals excellent stability of electrochromic characteristics for the radical cations generated, changing color from original pale yellowish neutral form to the green and then to dark blue oxidized forms. Furthermore, the anodically coloring of PAI-7a shows high coloration efficiency (CE = 205 cm2/C), high contrast of optical transmittance change (ΔT = 80% at 776 nm) and long-term redox reversibility. © 2014 Elsevier B.V. All rights reserved.

Chang H.-W.,University of Queensland | Kelly P.M.,University of Queensland | Shi Y.-N.,CAS Shenyang Institute of Metal Research | Zhang M.-X.,University of Queensland
Surface and Coatings Technology | Year: 2012

Nanostructured surface layers were produced on pure Al (AA196) and an Al-Si (A356) alloy plates using surface mechanical attrition treatment (SMAT) technique. Thermal stability of the refined grains in the nanocrystalline and sub-micron layers and in the adjacent deformation region induced by SMAT was investigated through characterization of the evolution of microstructure during post-SMAT annealing treatment within the temperature range from 150 to 370 °C for 1 and 24. h using both optical microscopy and transmission electron microscopy. Experimental results show that, during the annealing process, within the deformation region, typical recrystallization occurs, but, destabilization of the nanocrystalline and the sub-micron grains within the nanostructured layer and the sub-micron layer takes place through direct grain coarsening. It was also found, in both pure Al and A356 alloy, that nanocrystalline grains that are associated with high angle grain boundaries have higher thermal stability than the grains that are separated by low angle grain boundaries in the sub-micron layer. The possible grain coarsening mechanisms of these two types of grains are discussed. In addition, compared to SMATed pure Al samples, the broken eutectic Si particles in the SMATed A356 alloy dramatically enhance the thermal stability of the nanocrystalline grains, but have little effect on the sub-micron grains. Furthermore, it was also found that the thermal stability of the nanostructured grains in the SMATed affected zone in both alloys is independent on the SMAT duration. © 2012 Elsevier B.V.

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.

Wu C.,CAS Dalian Institute of Chemical Physics | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Journal of Materials Chemistry | Year: 2010

The development of hydrogen storage materials with high performance has been attracting considerable attention in recent years. Magnesium hydride, alanates, borohydrides and ammonia borane are the most promising candidates due to their high hydrogen capacity, but each type has its own shortcomings. In this short feature article, we highlight the current advances in the property enhancement of metal hydrides and complex hydrides by incorporating carbon materials, particularly carbon nanostructures such as nanotubes. Carbon with a small curvature radius exhibits prominent "catalytic" effect in conventional metal hydrides and complex hydrides. The smaller the curvature radius, the stronger the electronic affinity, and the stronger the interaction of carbon with hydrogen, which leads to a change of hydrogen release/combination energy, and consequently improving the de-/rehydrogenation kinetics. Meanwhile, the nanoconfinement effects of carbon scaffolds on all above hydrides were also discussed. © 2010 The Royal Society of Chemistry.

Bezares J.,University of California at San Diego | Jiao S.,University of Houston | Liu Y.,Texas A&M University | Bufford D.,Texas A&M University | And 4 more authors.
Acta Materialia | Year: 2012

Cyclic nano- and microindentation, along with indentation creep, were performed on nanotwinned Cu with two twin structures, and on nanotwinned Ag. The results provide evidence that nanotwinned face-centered cubic (fcc) structures are more stable than their nanocrystalline counterparts. The results are put in the important context of the available body of theoretical study of nanotwinned fcc metals, and in particular in the context of the theoretical forecasts of Kulkarni and Asaro [Kulkarni Y, Asaro RJ. Acta Mater 2009;57:2711]. It is shown, for example, that, as predicted, nanotwinned Ag displays performance comparable, if not superior, to nanotwinned Cu. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zheng Q.,CAS Shenyang Institute of Metal Research | Zheng Q.,Ningbo Branch of China Academy of Ordnance Science
Science of Advanced Materials | Year: 2012

The solidification microstructure of the master alloys (MAs) and slowly cooled alloys (SCAs) for Mg-Cu-Gd ternary system and the best glass former in Mg-Cu-Ag-Gd quaternary system were systematically investigated. the best ternary glass former alloy, Mg61Cu28Gd11, with a critical size (Dc) of 12 mm is correlated with a eutectic reaction L→Mg2Cu+Mg3CuGd in Mg-Cu-Gd equilibrium phase diagram. And a phase diagram was established for the studied compositions in the Mg-Cu-Gd ternary system. The glass forming ability (GFA) was dramatically improved when Cu is substituted by Ag. In Mg-Cu-Ag-Gd quaternary system, the critical size reached 27 mm for Mg59.5Cu22.9Ag6.6Gd11 and this is the largest Dc for all reported Mg-based bulk metallic glasses (BMGs). The reasons why the Mg59.5Cu22.9Ag6.6Gd11 has an extraordinary glass forming ability was explained from two aspects: stabilization of the liquid and frustration of thecompeting phase. © 2012 by American Scientific Publishers.

Li W.,CAS Beijing National Laboratory for Molecular | Gao Y.,CAS Beijing National Laboratory for Molecular | Chen W.,Zhejiang University of Technology | Tang P.,CAS Beijing National Laboratory for Molecular | And 4 more authors.
ACS Catalysis | Year: 2014

Nitrogen-doped graphene treated with ammonia under different temperatures was used as the catalysts for the epoxidation of trans-stilbene and styrene at 373 K. NG-800 (N-doped graphene treated at 800°C for 8 h) performed the best and gave the highest recyclable catalytic activity for the epoxidation of trans-stilbene, with 95.8% conversion and 94.4% selectivity to trans-stilbene epoxide. The catalytic center has been identified with the reaction mechanism elucidated by DFT calculation. © 2014 American Chemical Society.

Yuan Y.,Xuzhou Normal University | Li L.,Xuzhou Normal University | Wang C.,Xuzhou Normal University | Wang C.,CAS Shenyang Institute of Metal Research | Zhu Y.,Xuzhou Normal University
Electrochemistry Communications | Year: 2010

The effects of hydrogen on the pitting processes of X70 carbon steel in neutral chloride ions containing solution are investigated by using the scanning electrochemical microscope (SECM) technique. The tip of the SECM monitors the Fe2+ ions produced by the specimen during its anodic dissolution processes, thus the initiation and the propagation of the pitting processes can be observed. Pitting is much more easily observed after the specimen has been pre-charged with hydrogen, for the oxidation of the hydrogen in the X70 decreases the pH value at the X70/solution interface, which retards the formation of an oxide film and subsequently promotes the pitting processes. The observed behaviour is further verified by the decrease of the solution's pH. © 2010 Elsevier B.V. All rights reserved.

Liu D.X.,University of California at Irvine | Zhang Z.D.,CAS Shenyang Institute of Metal Research | Sun L.Z.,University of California at Irvine
Journal of Materials Research | Year: 2010

Because of the lack of universal contact models for nonlinear strain problems, indentation analysis on rubberlike materials is confined to small deformation in which Hertz's solution is applied. Recognizing that deep indentation may provide more material information, in this paper we propose a nonlinear elastic model for large spherical indentation of rubberlike materials based on the higher-order approximation of spherical function and Sneddon's solution. The effect of limiting network stretch is studied on the initial elastic modulus for lightly cross-linked rubbers. With the comparisons of the finiteelement simulation and the experimental result, the proposed model is verified to predict the large indentation of rubberlike materials over the indentation depth of 0.8 times the indenter radius. © 2010 Materials Research Society.

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 S.X.,CAS Shenyang Institute of Metal Research
International Materials Reviews | Year: 2012

The effect of inclusion size on fatigue behaviour of high strength steels in the very high cycle fatigue (VHCF) regime (.10 7-10 9 cycles) is reviewed. Internal fatigue fractures of high strength steels in the VHCF regime initiate mostly at non-metallic inclusions. The critical inclusion size below which it is hard to initiate fatigue cracking of high strength steels in the VHCF regime is found to be about half the critical value characteristic of the high cycle fatigue (HCF) regime (about 10 5-10 7 cycles). A stepwise or duplex S-N curve is observed in the VHCF regime. The shape and form of the S-N curves are affected by inclusion size and other factors including surface condition, residual stress, environment and loading modes. Fatigue strength and fatigue life for high strength steels have been found to obey inverse power laws with respect to inclusion size D of the form σ w∝D -n1 and Nf∝D -n2 respectively. For fatigue strength, the exponent n 1 has been reported to be ∼0·33 in the literature for the HCF regime and, more recently, to fall in the range 0·17-0·19 for the VHCF regime. For fatigue life, the exponent n2 is reported to be ∼3 in the HCF regime, and in the range 4·29-8·42 in the VHCF regime. A special area was often observed inside a 'fish eye' mark in the vicinity of a non-metallic inclusion acting as the fracture origin for specimens having a long fatigue life. The major mechanisms of formation for this special area are discussed. To estimate the fatigue strength and fatigue life, it is necessary to know the size of the maximum inclusion in a tested specimen, and to be able to infer this value using data from a small volume of steel. The statistics of extreme value (SEV) method and the generalised Pareto distribution (GPD) method are introduced and compared. Finally, unresolved problems and future work required in studying the VHCF of high strength steels are briefly presented. © 2012 Institute of Materials, Minerals and Mining and ASM International Published by Maney for the Institute and ASM International.

Shen W.,CAS Shenyang Institute of Metal Research | Shen W.,Ningbo Institute of Materials Technology and Engineering
Sensors and Actuators, B: Chemical | Year: 2012

SnO 2 precursor inks with appropriate viscosity and surface tension were prepared using the sol-gel technique with anhydrous ethanol as the primary solvent. The inks were printed on both alumina ceramic and silicon substrates using an ink printing apparatus produced by modifying a commercial printer. SnO 2 based gas-sensing films with different thicknesses and additives were formed, and the morphologies and electrical properties of these films were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and an instrument designed to measure the gas sensing abilities of the films. A linear relationship was observed between the natural logarithm of the electrical resistance of the SnO 2 films and the reciprocal of the films' absolute working temperature in the range between 20°C and 265°C. The electrical and gas-sensing properties of the films changed significantly with the thickness of the films. The film thickness can be easily adjusted by modifying the number of printing events. The SnO 2 films selectivity for various gases could be modified by utilizing different additives. This work also showed that ink-jet printing was a convenient and low-cost method to prepare gas-sensing films with controlled film thickness and additive level. © 2012 Elsevier B.V. All rights reserved.

Sachdev A.K.,General Motors | Kulkarni K.,General Motors | Fang Z.Z.,University of Utah | Yang R.,CAS Shenyang Institute of Metal Research | Girshov V.,Saint Petersburg State Polytechnic University
JOM | Year: 2012

Titanium offers performance as well as mass saving benefits in automotive components subjected to reciprocating and suspension loads and in components subjected to extreme temperatures and gradients. However, the extensive use of titanium is hampered by the high cost of the raw material and the special handling that is needed. This article outlines the technological and economic challenges faced and highlights some example materials and process developments that attempt to address these hurdles. © 2012 TMS.

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.

Singh A.,Massachusetts Institute of Technology | Dao M.,Massachusetts Institute of Technology | Lu L.,CAS Shenyang Institute of Metal Research | Suresh S.,Massachusetts Institute of Technology
Acta Materialia | Year: 2011

Nanotwinned metals have the potential for use as structural materials by virtue of having a combination of high strength as well as reasonable ductility and damage tolerance. In the current study, the tribological response of nanotwinned copper has been characterized under conditions of repeated frictional sliding contact with a conical tip diamond indenter. Pure ultrafine-grained copper specimens of fixed grain size (∼450 nm), but with three different structural conditions involving relatively high, medium and negligible concentrations of nanotwins, were studied. The effects of twin density and number of repetitions of sliding cycles on the evolution of friction and material pile-up around the diamond indenter were studied quantitatively by depth-sensing instrumented frictional sliding. Cross-sectional focused ion beam and scanning electron microscopy observations were used to systematically monitor deformation-induced structural changes as a function of the number of passes of repeated frictional sliding. Nanoindentation tests at the base of the sliding tracks coupled with large-deformation finite-element modeling simulations were used to assess local gradients in mechanical properties and deformation around the indenter track. The results indicate that friction evolution as well as local mechanical response is more strongly influenced by local structure evolution during repeated sliding than by the initial structure. An increase in twin density is found to result in smaller pile-up height and friction coefficient. Compared to the low-density nanotwinned metal, high-density nanotwinned copper showed significantly higher resistance to surface damage and structural changes, after the initial scratch. However with an increase in the number of sliding passes, the friction coefficient and rate of increase of pile up for all specimens acquire a steady value which does not change significantly in subsequent scratch passes. The frictional sliding experiments also lead to the striking result that copper specimens with both a high and low density of nanotwins eventually converge to a similar microstructure underneath the indenter after repeated tribological deformation. This trend strongly mirrors the well-known steady-state response of microcrystalline copper subjected to uniaxial cyclic loading. General perspectives on contact fatigue response of nanotwinned copper are developed on the basis of these new findings. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

Wu E.,Chinese Academy of Sciences | Li W.,Chinese Academy of Sciences | Li J.,CAS Shenyang Institute of Metal Research
International Journal of Hydrogen Energy | Year: 2012

In activation of hydrogen storage alloys, the nickel-group metals, especially Pd, act as the catalysts to dissociate hydrogen and turn the alloys into successful hydrogen absorbers. The Laves phase Sc and Zr alloys with Cr-Mn as common components exhibit extraordinary hydrogen activation properties matching Pd. Through a cracking mechanism, the bulk samples of these alloys rapidly absorb hydrogen at sub-atmospheric pressures and room-temperature, achieve absorption performance of those Pd surface-modified alloys, meanwhile retaining good reversibility. Among them, the ScCrMn exhibits significantly higher absorption rate than Pd, whereas, the ZrCrMn shows similar absorption kinetics and reversibility to Pd. The shortest initial-activation-time, highest initial-activation-rate and lowest allowed-activation-pressure achieved by ScCrMn are 15 s, -16.6 kPa/s and 0.46 kPa, respectively, in comparison with those of 18 s, 3.2 kPa/s and 0.13 kPa for Pd powder measured under equivalent conditions. The findings and associated magnetization measurements indicate that Cr and Mn upon alloying with certain lower valence metals possess surface electronic structures highly beneficial to hydrogen dissociation. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Xu X.,University of St. Andrews | Liu G.,CAS Shenyang Institute of Metal Research | Randorn C.,University of St. Andrews | Irvine J.T.S.,University of St. Andrews
International Journal of Hydrogen Energy | Year: 2011

A highly active photocatalyst based on g-C3N4 coated SrTiO3 has been synthesized simply by decomposing urea in the presence of SrTiO3 at 400 °C. The catalyst demonstrates a high H2 production rate ∼440 μmol h-1/g catalyst in aqueous solution under visible light irradiation, which is much higher than conventional anion doped SrTiO3 or physical mixtures of g-C 3N4 and SrTiO3. The improved photocatalytic activity can be ascribed to the close interfacial connections between g-C 3N4 and SrTiO3 where photo-generated electron and holes are effectively separated. The newly synthesized catalyst also exhibited a stable performance in the repeated experiments. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Zuo C.,Heilongjiang University | Wen J.,Heilongjiang University | Zhu S.,CAS Shenyang Institute of Metal Research | Zhong C.,Wuhan University
Optical Materials | Year: 2010

The electronic structures of C, C-Al and C-Ga doped ZnO were investigated from the first-principles based on density functional theory (DFT). It was found that the C-doped ZnO where 1/8 Os are substituted by C is p-type with hole carriers locating nearby valence band maximum. Moreover, the Madelung energy increases in this case. Incorporating the reactive donor Al or Ga into C-doped ZnO system at Zn sites, not only enhances the C acceptor concentration, but also gets a shallower C acceptor energy level in the band gap in p-type codoped ZnO crystals and decreases the Madelung energy. © 2009 Elsevier B.V. All rights reserved.

Wang D.-W.,University of Queensland | Su D.,CAS Shenyang Institute of Metal Research
Energy and Environmental Science | Year: 2014

Heterogeneous nanocarbon materials are being increasingly investigated and deployed in numerous new technologies and devices for sustainable energy conversion and storage. Nanocarbons often consist of fullerene, graphene and carbon nanotubes. Their derivatives include quantum dots, nanofibres, nanoribbons, nanospheres/capsules and other nanostructured morphologies. The heterogeneous forms of these nanocarbons stem from the implantation of alien atoms into the aromatic carbon lattice or the covalent grafting of functional groups onto the carbon basal plane or edge sites. Heterogeneous nanocarbons have shown remarkable advantages in solar cells, water splitting, supercapacitors, lithium ion batteries and catalysis. This review focuses on recent progress in the experimental and computational studies of the roles of heteroatoms in heterogeneous nanocarbons for electrocatalytic oxygen reduction reaction (ORR). Critical perspectives are devoted to the ambiguous phenomena in this emerging research area. The long standing debate about the active sites is discussed with an emphasis on more rational development of advanced nanocarbon-based electrocatalysts for ORR. © The Royal Society of Chemistry.

Yin S.M.,Shenyang University of Chemical Technology | Li S.X.,CAS Shenyang Institute of Metal Research
Journal of Materials Science and Technology | Year: 2013

Cyclic deformation and fatigue behaviors of Mg-12%Gd-3%Y-0.5%Zr (wt%, GW123K) alloy were investigated at room temperature under axial cyclic loading in strain controlled condition. It is shown that conventional extruded GW123K alloy maintained cyclic stability at strain amplitudes ranging from 2×10-3 to 10-2. The pronounced symmetric hysteresis loops were also observed during cyclic loading. Fracture surface observations indicated that fatigue cracks mainly initiated at large Gd-riched phase or at inclusion clusters at surface or subsurface, and grain boundary (GB) and slip bands (SBs) are also preferential sites for micro-crack incubation. © 2013.

Peng W.,Northwestern Polytechnical University | Zeng W.,Northwestern Polytechnical University | Wang Q.,CAS Shenyang Institute of Metal Research | Yu H.,Northwestern Polytechnical University
Materials and Design | Year: 2013

Hot compression of as-cast Ti60 titanium alloy at the deformation temperatures ranging from 970 to 1120°C with an interval of 30°C, the strain rates ranging from 0.01 to 10.0s-1 and the height reduction of 75% is conducted on a Gleeble-3500 thermo-mechanical simulator. The experimental stress-strain data from hot compression are employed to develop the Arrhenius-type constitutive model incorporating the strain effect and artificial neural network (ANN) model with a back-propagation learning algorithm. The strain compensated constitutive model can track the experimental data across the whole hot working domain other than that at high strain rates (≥1s-1). It is possibly associated with the deformation mechanisms at high strain rates, where microstructure exhibits bands of flow localization and longitudinal cracking, are far different from that at low strain rates (≤0.1s-1) where dynamic recrystallization occurs. Comparison of the predicted results of flow stress based on the ANN model and those acquired from the strain compensated constitutive model has been performed. It is found that the relative error of the ANN model varies from -3.42% to 4.33% while that of the strain compensated constitutive model ranges from -14.65% to 13.63%, and the average absolute relative error is 2.41% and 8.45% corresponding to the ANN model and strain compensated constitutive model, respectively. These results sufficiently indicate that the ANN model is more accurate and efficient in terms of predicting the flow stress of as-cast Ti60 titanium alloy. © 2013.

Zhu L.,Zhejiang University | Zhu L.,Hong Kong Polytechnic University | Shi S.,Hong Kong Polytechnic University | Lu K.,CAS Shenyang Institute of Metal Research | Lu J.,City University of Hong Kong
Acta Materialia | Year: 2012

A statistical analysis is employed to investigate the mechanical performance of nanostructured metals with bimodal grain size distribution. The contributions of microcracks in the plastic deformation are accounted for in the mechanism-based plastic model used to describe the strength and ductility of the bimodal metals. The strain-based Weibull probability distribution function and percolation analysis of microcracked solids are applied to predict the failure behavior of the bimodal metals. The numerical results show that the proposed model can describe the mechanical properties of the bimodal metals, including yield strength, strain hardening and uniform elongation. These predictions agree well with the experimental results. The stochastic approaches adopted in the proposed model successfully capture the failure behavior of bimodal coppers that are sensitive to grain size and the volume fraction of coarse grains in addition to the corresponding threshold for percolation. These results will benefit the optimization of both strength and ductility by controlling constituent fractions and the size of the microstructures in materials. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zhu Y.,North Carolina State University | Valiev R.Z.,Institute of Physics of Advanced Materials | Langdon T.G.,University of Southern California | Tsuji N.,Kyoto University | Lu K.,CAS Shenyang Institute of Metal Research
MRS Bulletin | Year: 2010

Plastic deformation can effectively produce nanostructured metals and alloys in bulk or surface-layer forms that are suitable for practical structural or functional applications. Such nanostructured materials are porosity-free and contamination-free, and therefore they are ideal for studying fundamental mechanisms and mechanical properties. In this article, we first give an overview of the principles of grain refinement by plastic deformation and an introduction to the reported processing techniques. Then the four most-developed and promising techniques will be described in detail: equal-channel angular pressing, high-pressure torsion, accumulative roll bonding for bulk nanostructured metals, and surface mechanical attrition treatment for nanostructured surface layers.

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.

Dong J.-H.,CAS Shenyang Institute of Metal Research
Corrosion Science and Protection Technology | Year: 2010

In this paper, the rusting evolution of low Mn-Cu alloyed steel in a simulated coastal environment was studied by cyclic wet/dry accelerated corrosion test(CCT). It showed that the corrosion rate increased with increasing the CCT cycles in the initial stage of CCT, whereafter it decreased with increasing the CCT cycles in the subsequent stage. The polarization behavior of the rusted steel indicated that the corrosion product promoted the cathodic process while restrained the anodic process. During the initial rusting stage, the rust showed a loose structure and low content of α- FeOOH. Whereafter the rust became dense and the content of α-FeOOH increased.

Zhou L.,Shenyang Ligong University | Zhou L.,CAS Shenyang Institute of Metal Research | Li S.,Shenyang Ligong University | Huang S.,Shenyang Ligong University
Materials and Design | Year: 2011

By using the constitutive equation based on the mechanism-based strain gradient plasticity with finite element software, the yield strength, uniform elongation, and toughness of aluminum alloy 6063 with different grain sizes, different particle diameters and volume fractions were studied numerically. The toughness is defined as the product of yield strength and uniform elongation. The calculation results indicate that the grain refinement and particle refinement cannot substantially improve the uniform elongation but can increase the yield strength of Al alloy when the grain size is on the order of the micron and submicron scale. When the grain size less than 2 μm, Al alloys usually exhibit high strength and low uniform elongation, and when the grain size greater than 5 μm, the materials exhibit low strength and high elongation; in either case the toughness is low. However, in the grain size of several micrometers, the toughness of Al alloy is the highest. © 2010 Elsevier Ltd.

Bao Z.,Chinese University of Hong Kong | Sun Z.,CAS Shenyang Institute of Metal Research | Xiao M.,Chinese University of Hong Kong | Chen H.,Chinese University of Hong Kong | And 2 more authors.
Journal of Materials Chemistry | Year: 2011

An approach for the transverse oxidation of Au nanorods has been demonstrated by selectively capping the ends of the nanorods with Ag 2O through a hydrothermal reaction. The tight Ag2O capping protects the ends of the nanorods and restricts oxidation to occurring only at the side surfaces. Such transverse oxidation leads to a gradual reduction in the effective diameter of the nanorods, an increase in the effective aspect ratio, and therefore a red shift in the longitudinal plasmon resonance. The red shift in the longitudinal plasmon resonance can reach up to 250 nm and be controlled by varying the oxidation time. In addition, the Ag2O capping and transverse oxidation process is also applicable for Au nanorods with different longitudinal plasmon resonance wavelengths. Furthermore, the transverse oxidation is nonuniform. It produces dimples on the side surfaces of the Au nanorods. Numerical electrodynamic calculations indicate that the oxidized nanorods exhibit stronger electric field intensity enhancements at the dimples for both the longitudinal and transverse plasmon resonances in comparison to the unoxidized nanorods. We believe that this transverse oxidation approach will be beneficial to the design and preparation of Au nanostructures for various biotechnological applications. © 2011 The Royal Society of Chemistry.

Zhang Y.,Northeastern University China | Zhang Y.,University of Munster | Yang B.,CAS Shenyang Institute of Metal Research | Wilde G.,Northeastern University China
Journal of Alloys and Compounds | Year: 2014

Magnetism and magnetocaloric effect in REAgAl (RE = Er and Ho) intermetallic compounds have been studied. Both compounds undergo a second order magnetic phase transition from paramagnetic to ferromagnetic state. A large reversible magnetocaloric effect was observed around its own Curie temperatures TC∼ 14 and 18 K for ErAgAl and HoAgAl, respectively. For a field change of 0-7 T, the maximum magnetic entropy change reaches 13.7 and 13.8 J/kg K for RE = Er and Ho, respectively. The corresponding relative cooling powers are evaluated to be 398 and 525 J/kg. © 2014 Elsevier B.V. All rights reserved.

Sun D.-M.,Nagoya University | Sun D.-M.,CAS Shenyang Institute of Metal Research | Timmermans M.Y.,Aalto University | Kaskela A.,Aalto University | And 6 more authors.
Nature Communications | Year: 2013

A variety of plastic products, ranging from those for daily necessities to electronics products and medical devices, are produced by moulding techniques. The incorporation of electronic circuits into various plastic products is limited by the brittle nature of silicon wafers. Here we report mouldable integrated circuits for the first time. The devices are composed entirely of carbon-based materials, that is, their active channels and passive elements are all fabricated from stretchable and thermostable assemblies of carbon nanotubes, with plastic polymer dielectric layers and substrates. The all-carbon thin-film transistors exhibit a mobility of 1,027 cm 2 V -1 s -1 and an ON/OFF ratio of 10 5. The devices also exhibit extreme biaxial stretchability of up to 18% when subjected to thermopressure forming. We demonstrate functional integrated circuits that can be moulded into a three-dimensional dome. Such mouldable electronics open new possibilities by allowing for the addition of electronic/plastic-like functionalities to plastic/electronic products, improving their designability. © 2013 Macmillan Publishers Limited.

Guo X.,Harbin Institute of Technology | Guo X.,CAS Shenyang Institute of Metal Research | An M.,Harbin Institute of Technology
Corrosion Science | Year: 2010

A bilayer on AZ31B magnesium alloy was prepared by first applying anodization to modify the substrate, and then depositing a self-assembled nanophase particle (SANP) film. Structure and corrosion behaviour are characterized by scanning electron microscopy, energy dispersion spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope and electrochemical impedance spectroscopy. Experimental results indicate that the bilayer consists of a SNAP/loose layer and a dense layer, and provides the corrosion protection of Mg substrate for more than 354. h in 0.005. M NaCl solution. Therefore, the bilayer is effective to protect Mg alloy against corrosion for a long time. © 2010 Elsevier Ltd.

Peng Q.,CAS Shenyang Institute of Metal Research | Peng Q.,Tohoku University | Hou J.,Tohoku University | Takeda Y.,Tohoku University | Shoji T.,Tohoku University
Corrosion Science | Year: 2013

Effects of chemical composition on grain boundary microchemistry and stress corrosion cracking (SCC) in two kinds of modified Alloy 182 with different hot-cracking resistance were investigated. The results showed that while decreasing concentrations of C, P and S but increasing the concentration ratio of (Nb. +. Ta)/Si can enhance hot-cracking resistance of the alloy, SCC susceptibility in primary water was promoted simultaneously, which is most likely due to the lowered creep resistance by a lower precipitate density and less P segregation at the grain boundary in the alloy. © 2012 Elsevier Ltd.

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.

Su D.S.,CAS Shenyang Institute of Metal Research | Su D.S.,Fritz Haber Institute of the Max Planck Society | Perathoner S.,Messina University | Centi G.,Messina University
Catalysis Today | Year: 2012

This introductory contribution to the special issue of Catalysis Today is dedicated to selected contributions presented at the Carbocat-IV (Carbon for Catalysis) Symposium held in Dalian (China) on November 7-10 (2010). The introduction first shortly overviews the main reasons for the interest on carbon materials for catalysis and the elements of novelty discussed on the contributions of this issue, and then provide a concise outline of the general trends and developments in this field to give a glimpse on the progresses in the field, and on the perspectives of this exciting area of catalysis. © 2012 Elsevier B.V.

Zhang Z.-D.,CAS Shenyang Institute of Metal Research
Chinese Physics B | Year: 2013

An overview of the mathematical structure of the three-dimensional (3D) Ising model is given from the points of view of topology, algebra, and geometry. By analyzing the relationships among transfer matrices of the 3D Ising model, Reidemeister moves in the knot theory, Yang-Baxter and tetrahedron equations, the following facts are illustrated for the 3D Ising model. 1) The complex quaternion basis constructed for the 3D Ising model naturally represents the rotation in a (3+1)-dimensional space-time as a relativistic quantum statistical mechanics model, which is consistent with the 4-fold integrand of the partition function obtained by taking the time average. 2) A unitary transformation with a matrix that is a spin representation in 2n·l·o-space corresponds to a rotation in 2n·l·o-space, which serves to smooth all the crossings in the transfer matrices and contributes the non-trivial topological part of the partition function of the 3D Ising model. 3) A tetrahedron relationship would ensure the commutativity of the transfer matrices and the integrability of the 3D Ising model, and its existence is guaranteed by the Jordan algebra and the Jordan-von Neumann-Wigner procedures. 4) The unitary transformation for smoothing the crossings in the transfer matrices changes the wave functions by complex phases φx, φy, and φz. The relationship with quantum field and gauge theories and the physical significance of the weight factors are discussed in detail. The conjectured exact solution is compared with numerical results, and the singularities at/near infinite temperature are inspected. The analyticity in β = 1/(kBT) of both the hard-core and the Ising models has been proved only for β > 0, not for β = 0. Thus the high-temperature series cannot serve as a standard for judging a putative exact solution of the 3D Ising model. © 2013 Chinese Physical Society and IOP Publishing Ltd.

Wang S.,CAS Shenyang Institute of Metal Research
Journal of the Physical Society of Japan | Year: 2010

In this study, we implement.rst-principles calculation to study the physical and chemical properties of two-dimensional (2D) hexagonal crystals. The ab initio results of the crystallographic, elastic, and electronic band-gap parameters of C, Si, Ge, BN, CN, SiN, and SiC monolayers are presented. Similarly to graphene, CN and BN are among compounds with the highest 2D elasticity. The in-plane elastic moduli of Si and Ge monolayers are relative small. C, Si, and Ge monolayers are semimetal. All the four binary 2D crystals are semiconductors with wide band gaps. Two typical 2D hexagonal lattice structures, i.e., sp2 flat and sp3 rumpled configurations, are classified. The orbital sp2-hybridization in graphene and 2D BN is veri.ed by angular-momentum projected atomic density of state calculation. 2D SiC is basically in sp2-hybridization. The orbital hybridization of Si, Ge, CN, and SiN monolayers is of the sp3-type on the whole. In view of the structural and chemical features of these monolayers, di.erent methods for the experimental preparation of 2D crystals are suggested. © 2010 The Physical Society of Japan.

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.

Zhang L.,Northeastern University China | Wang S.,CAS Shenyang Institute of Metal Research
Journal of Nanoscience and Nanotechnology | Year: 2010

Structural changes of Au clusters respectively containing 603 and 675 atoms with their (100) facts supported on MgO(010) surfaces at 5 K have been investigated by molecular-dynamics simulations on the atomic interchange potentials of the metal/MgO interface, which parameters are from the Ab initio energies using Chen-Möbius inversion method. As the interaction time evolves, the structural changes accompanying with atom movements are determined by decomposing peaks of pair distribution functions (PDF5) according to the pair analysis (PA) technique, and local structure patterns are identified for the supported clusters. It is shown that there exist deformation processes the two Au clusters to adjust their atom distances owing to atom misfits among the clusters and the MgO support. Concerning these supported clusters, the obtained results reveal how the cluster size and the interaction affect the structural changes in the interaction between the supported cluster and the MgO support. Copyright © 2010 American Scientific Publishers.

Su D.S.,Fritz Haber Institute of the Max Planck Society | Su D.S.,CAS Shenyang Institute of Metal Research | Schlogl R.,Fritz Haber Institute of the Max Planck Society
ChemSusChem | Year: 2010

Electrochemical energy storage is one of the important technologies for a sustainable future of our society, in times of energy crisis. Lithium-ion batteries and supercapacitors with their high energy or power densities, portability, and promising cycling life are the cores of future technologies. This Review describes some materials science aspects on nanocarbonbased materials for these applications. Nanostructuring (decreasing dimensions) and nanoarchitecturing (combining or assembling several nanometer-scale building blocks) are landmarks in the development of high-performance electrodes for with long cycle lifes and high safety. Numerous works reviewed herein have shown higher performances for such electrodes, but mostly give diverse values that show no converging tendency towards future development. The lack of knowledge about interface processes and defect dynamics of electrodes, as well as the missing cooperation between material scientists, electrochemists, and battery engineers, are reasons for the currently widespread trial-and-error strategy of experiments. A concerted action between all of these disciplines is a prerequisite for the future development of electrochemical energy storage devices. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tang W.N.,Korea Institute of Materials Science | Tang W.N.,CAS Shenyang Institute of Metal Research | Park S.S.,Korea Institute of Materials Science | You B.S.,Korea Institute of Materials Science
Materials and Design | Year: 2011

Mg-5Sn-xZn alloys with varying Zn contents were subjected to indirect extrusion and the effects of the Zn content on the microstructure and mechanical properties of the as-extruded alloys were investigated. It was found that, the grain size and the basal texture are basically similar, however, the amount of fine particles consisting of Mg2Sn and MgZn phases increases markedly as the Zn content increases. A higher number of these particles would be responsible for the better comprehensive mechanical properties as well as a lower degree of yield asymmetry. © 2011 Elsevier Ltd.

Guo J.-T.,CAS Shenyang Institute of Metal Research
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2011

The effects of several minor elements on the microstructure and mechanical properties of superalloys were studied. The roles of minor elements in grain boundary cohesion, grain boundary precipitation and solidification segregation were discussed. The results show that a proper quantity of B, C, Y, La, Ce, Zr or Mg can significantly improve the stress-rupture property of superalloys, whereas Si and S degrade it remarkably; in addition, P is beneficial to some wrought superalloys, while it is harmful to some cast superalloys.

Zhang L.C.,University of Western Australia | Klemm D.,Leibniz Institute for Solid State and Materials Research | Eckert J.,Leibniz Institute for Solid State and Materials Research | Eckert J.,TU Dresden | And 2 more authors.
Scripta Materialia | Year: 2011

In this paper, we present the results of using selective laser melting (SLM) to produce biomedical beta Ti-24Nb-4Zr-8Sn components, including the manufacture of a sample acetabular cup. The density of the material increases with increasing incident laser energy (i.e. decreasing laser scan speed) and reaches a near full density value of >99% without any post-processing. The mechanical properties of the as-processed material are also compared to those of conventionally processed material. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zhou Y.,Aerospace Research Institute of Materials And Processing Technology | Liu B.,CAS Shenyang Institute of Metal Research
Journal of the European Ceramic Society | Year: 2013

Minimum lattice thermal conductivities and mechanical properties of polymorphous MPO4 (M=Al, Ga) are investigated by first principles calculations. The theoretical minimum thermal conductivities are found to be 1.02W(mK)-1 for α-AlPO4, 1.20W(mK)-1 for β-AlPO4, 0.87W(mK)-1 for α-GaPO4 and 0.88W(mK)-1 for β-GaPO4. The lower thermal conductivities in comparison to YSZ can be attributed to the lattice phonon scattering due to the framework of heterogeneous bonds. In addition, the low shear-to-bulk modulus ratio for both β-AlPO4 (0.38) and β-GaPO4 (0.30) is observed. Our results suggest their applications as light-weight thermal insulator and damage-tolerant/machinable ceramics. © 2013 Elsevier Ltd.

Mahbubul Haque M.,Tohoku University | Yin L.,CAS Shenyang Institute of Metal Research | Nugraha A.R.T.,Tohoku University | Saito R.,Tohoku University
Carbon | Year: 2011

The bond-stretching phonon modes of linear polyynes with hydrogen atom termination at the both ends are calculated as a function of chain length within the density functional theory. The frequency of one of two particular Raman active phonon modes monotonically decreases with the increase of polyyne chain length while that of the other one shows an oscillating behavior, consistent with previous Raman measurements. The relative Raman intensity of the two phonon modes are evaluated by optimized geometries for ground states and excited states. We also present a nuclear magnetic resonance (NMR) calculation for spin-spin coupling constants as a function of distance between hydrogen and carbon-13 nuclei and, within carbon-13 nuclei, up to the polyyne center of symmetry. We compare the calculated results with recent NMR experiments. © 2011 Elsevier Ltd. All rights reserved.

Zhang S.Z.,Yantai University | Li M.M.,Yantai University | Yang R.,CAS Shenyang Institute of Metal Research
Materials Characterization | Year: 2011

The present work evaluates the influence of bulk carbon content and aging temperature on the stability of carbide in near alpha Ti-5.6Al-4.8Sn-2Zr-1Mo-0. 35Si-0.7Nd titanium alloy. The carbide particles were formed during heat treatment in the β phase field and preserved by water quenching. Subsequent aging treatments at 750-850 °C caused partial dissolution of these precipitates, as a result of the peritectoid reaction between the β phase and carbide. The models based on interface reaction controlled dissolution, via uniform atomic detachment, dislocation mechanism or vacancy flow, yielded experimental predictions comparable to the observed dissolution kinetics. Furnace cooling after heat treatment in the β phase field dissolved carbide particles completely, and the microstructure changed from acicular-like or block α to equiaxed α with increase of carbon content. © 2011 Elsevier Inc. All rights reserved.

Peng X.,CAS Shenyang Institute of Metal Research
Nanoscale | Year: 2010

Structural considerations for designing a high-temperature oxidation-resistant metallic material are proposed, based on the dependence of the material structure on a promotion of the development of a protective scale of chromia or alumina. The material should have numerous sites on its surface for nucleating the protective oxides at the onset of oxidation and abundant grain boundaries in deeper areas for simultaneously supplying sufficient flux of the protective-oxide-forming elements toward the surface for a rapid linkage of the oxide nuclei through their lateral growth. Based on these considerations, we fabricated, using an electrochemical deposition method, novel nanocomposites which have a nanocrystalline metal matrix containing Cr and/or Al nanoparticles dispersed at the nano length scale. The validity of the design considerations is verified by comparing the high-temperature oxidation of a typical Ni-Cr nanocomposite system with two types of conventional Ni-Cr materials having similar or higher Cr content but different structure: one is a composite having a nanocrystalline Ni matrix containing Cr microparticles dispersed at the microscale and the other are micron-grained Ni-Cr alloys with the Cr distribution at the atomic length scale.

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.

Cui C.Y.,CAS Shenyang Institute of Metal Research | Gu Y.F.,Japan National Institute of Materials Science | Yuan Y.,Japan National Institute of Materials Science | Harada H.,Japan National Institute of Materials Science
Scripta Materialia | Year: 2011

Dynamic strain aging (DSA) in a newly developed Ni-Co superalloy, TMW-2, was examined at temperatures ranging from room temperature to 600°C and strain rates between 3 × 10-2 and 8 × 10-5 s-1. The alloy exhibited both normal and inverse DSA effects at the temperatures and strain rates tested. Transmission electron microscopy evidence suggests that the normal behavior is associated with conventional DSA due to dynamic dislocation-solute interaction, while the inverse behavior may be related to the occurrence of stacking faults. © 2010 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.

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.

Zhang R.,Tsinghua University | Wen Q.,Tsinghua University | Qian W.,Tsinghua University | Su D.S.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Advanced Materials | Year: 2011

Superstrong, ultralong, individual carbon nanotubes (CNTs) are deposited with TiO 2 particles and visualized under an optical microscope with excellent strain-relaxation reversibility and high fatigue resistance capability. The CNTs with perfect structures have tensile strengths of up to 200 GPa, densities to 1.34 TPa, energy density as high as 1125 Wh kg -1 and the power density can be up to 144 MW kg -1 for mechanical energy storage. The superb mechanical properties confirm the potential of an individual CNT as an effective storage medium with mechanical energy for nano-electromechanical systems, flexible devices, sensors, actuators, antennas, etc. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chen J.,CAS Shenyang Institute of Metal Research | Zhang Y.,Beijing Institute of Technology | Deng C.,Beijing Institute of Technology | Dai X.,Beijing Institute of Technology
Materials Chemistry and Physics | Year: 2010

The crystallization kinetics in the glass system BaxSr1-xTiO3-Al2O3-SiO2 prepared via the conventional melt-quenching technique has been studied by isothermal method using differential scanning calorimetry (DSC). X-ray powder diffraction studies carried out on heat-treated (850-1100 °C) glasses reveal the evolution of BaxSr1-xTiO3 crystalline phase along with a second phase of BaAl2Si2O8. The exponent n in the Johnson-Mehl-Avrami (JMA) equation applied to the isothermal process is in the range of 2.3-2.73. The apparent activation energy for BaxSr1-xTiO3 crystal growth obtained from JMA equation under isothermal condition is 457 kJ mol-1, which is close to the dissociation energy of Si-O bonds. Moreover, there is no remarkably different effect between one-stage and two-stage heat treatment procedures on the microstructures and dielectric properties of barium strontium titanate based glass-ceramics in the present study, according to structure-property analysis. © 2010 Elsevier B.V. All rights reserved.

Chen X.-Q.,Oak Ridge National Laboratory | Chen X.-Q.,CAS Shenyang Institute of Metal Research | Fu C.L.,Oak Ridge National Laboratory | Franchini C.,University of Vienna
Journal of Physics Condensed Matter | Year: 2010

The immense interest in carbon nanomaterials continues to stimulate intense research activities aimed at realizing carbon nanowires, since linear chains of carbon atoms are expected to display novel and technologically relevant optical, electrical and mechanical properties. Although various allotropes of carbon (e.g., diamond, nanotubes, graphene, etc) are among the best-known materials, it remains challenging to stabilize carbon in the one-dimensional form because of the difficulty of suitably saturating the dangling bonds of carbon. Here, we show through first-principles calculations that ordered polymeric carbon chains can be stabilized in solid Li2C2 under moderate pressure. This pressure-induced phase (above 5 GPa) consists of parallel arrays of twofold zigzag carbon chains embedded in lithium cages, which display a metallic character due to the formation of partially occupied carbon lone-pair states in sp2-like hybrids. It is found that this phase remains the most favorable one in a wide range of pressures. At extreme pressure (larger than 215 GPa) a structural and electronic phase transition towards an insulating single-bonded threefold-coordinated carbon network is predicted. © 2010 IOP Publishing Ltd.

Liu G.Q.,Northeastern University China | Wen L.,CAS Shenyang Institute of Metal Research | Liu Y.M.,Northeastern University China
Journal of Solid State Electrochemistry | Year: 2010

The spinel material LiNi 0.5Mn 1.5O 4 displays a remarkable property of high charge/discharge voltage plateau at around 4.7 V. It is a promising cathode material for new-generation lithium-ion batteries with high voltage. Recently, a lot of researches related to this material have been carried out. In this review we present a summary of these researches, including the structure, the mechanism of high voltage, and the latest developments in improving its electrochemical properties like rate ability and cycle performance at elevated temperature, etc. Doping element and synthesizing nanoscale material are effective ways to improve its rate ability. The novel battery systems, like LiNi 0.5Mn 1.5O 4/Li 5Ti 4O 12 with good electrochemical properties, are also in progress. © 2010 Springer-Verlag.

Yin H.,Wuhan University | Tang D.,Wuhan University | Zhu H.,Wuhan University | Zhang Y.,China Institute of Atomic Energy | And 2 more authors.
Electrochemistry Communications | Year: 2011

Iron oxide was electrochemically split into iron and oxygen gas in molten Na 2CO 3-K 2CO 3 at 750 °C using a solid iron oxide cathode and a Ni10Cu11Fe alloy inert anode. Fe 2O 3 was electrochemically reduced to Fe on the cathode, releasing oxygen anions into the electrolyte and which were oxidized on the anode to generate O2. The cathodic current efficiency was as high as 95% and the energy consumption for producing 1 kg iron was 2.87 kWh, only half of the current industrial energy consumption of blast-furnace steel production. Due to the cost-affordable inert anode and the high energy efficiency, the method demonstrated in this work shows promise as a practical "green" iron production process. © 2011 Elsevier B.V. All rights reserved.

Su D.-S.,CAS Shenyang Institute of Metal Research | Schlogl R.,Fritz Haber Institute of the Max Planck Society
ChemSusChem | Year: 2016

Special Issue: Energy Conversion and Storage. Critical issues in current energy-based societies are its generation through methods utilizing alternatives to fossil fuels as well as its storage. Considering the scope, it is not surprising that the research becomes more and more multidisciplinary. Therefore, it is important to keep focused. The ChemEner symposia, the last one being highlighted in this Special Issue, achieve this by focusing on the state of the art and the newest development of the Chemistry of hydrogen generation, carbon dioxide reduction, and other related topics, exploring new concepts for clean future energy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li B.Q.,CAS Shenyang Institute of Metal Research | Sui M.L.,Beijing University of Technology | Mao S.X.,University of Pittsburgh
Journal of Materials Science and Technology | Year: 2011

Inherent twinnability of face-centered-cubic (fee) metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation, with which the twinnability of fee metals can be simply expressed as function of the stacking-fault energy, the unstable stacking-fault energy, and the unstable twinning-fault energy of fee metals. The predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters. © 2011 The Chinese Society for Metals.

Zhu W.,Shandong University | Zhu W.,University of Jinan | Chen T.,Shandong University | Ma X.,Shandong University | And 2 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2013

Highly dispersed hollow gold-graphene (HAu-G) nanocomposites were synthesized by a two-step method. The immobilization of hollow gold nanoparticles (HAu NPs) onto the surface of graphene sheets was achieved by mixing an aqueous solution of HAu NPs with a poly(N-vinylpyrrolidone)-functionalized graphene dispersion at room temperature. A glassy carbon electrode (GCE) was modified with the nanocomposites, and the as-prepared modified electrode displayed high electrocatalytic activity and extraordinary electronic transport properties. Amperometric detection of dopamine (DA) performed with the HAu-G modified electrode exhibits a good linearity between 0.08 and 600. μM with a low detection limit of 0.05. μM (S/N. = 3) and also possesses good reproducibility and operational stability. The interference of ascorbic acid (AA) and uric acid (UA) can be excluded when using differential pulse voltammetric technique. In addition, this type of modified electrode can also be applied to the determination of DA content in dopamine hydrochloride injection. It is obvious that the HAu-G modified electrode provides a new way to detect dopamine sensitively and selectively. © 2013 Elsevier B.V.

Liu H.,Northeastern University China | Xu Q.,Northeastern University China | Yan C.,CAS Shenyang Institute of Metal Research
Electrochemistry Communications | Year: 2013

The electrochemical corrosion of the graphite electrode for vanadium redox flow battery is investigated by on-line mass spectrometry analysis. The results show that CO2 and CO form and evolve more preferably than O 2 on the graphite anode, which lead to the electrochemical corrosion of the graphite electrode. Furthermore, the evolution rate of O2 is the highest one among evolved gases if the polarization potential becomes too positive. The oxidation of VO2 + on the graphite electrode in 2 M H2SO4 + 2 M VOSO4 hinders the carbon oxidation reaction and retards the electrochemical corrosion of the graphite electrode. © 2012 Elsevier B.V.

Zhang Z.-D.,CAS Shenyang Institute of Metal Research
Wuli Xuebao/Acta Physica Sinica | Year: 2015

This article first gives a brief review of magnetic structures, magnetic domains and topological magnetic textures and their relations. On the one hand, the magnetic domains are determined by the magnetic structures, the intrinsic magnetic properties and the micro-structural factors of a material. On the other hand, the magnetic domains could control the magnetization and demagnetization processes and also the technical magnetic properties of a material. Topology is found to have a close relation with physical properties of material. Recent interest has focused on topological magnetic textures, such as vortex, bubble, meron, skyrmion, and it has been found that the topological behaviors of these topological textures are closely related with magnetic properties of a material. Then this article introduces recent advances in magnetic structures, magnetic domains and topological magnetic textures, from views of the size effect, defects and interfaces. Finally, this article reviews briefly some results of investigation on the relations between microstructures, magnetic domains and magnetic properties of rare-earth permanent magnetic thin films, the topological magnetic textures and their dynamic behaviors of exchange coupled nanodisks. It has been concluded from the reviews on the literature that the investigation on anisotropic exchange-coupled rare-earth permanent magnets with high performance benefits the high efficient utilization of rare-earth resources. One could achieve optimal magnetic properties through magnetic domain engineering by adjusting the microstructures of magnetic materials. The concepts of topology is applied to various research fields, while the contributions from topological behaviors to physical properties are discovered in different materials. The researches on magnetic domains, topological magnetic ground state and excitation states and their dynamic behaviors are very important for a better understanding of quantum topological phase transitions and other topological relevant phenomena. It can be quite helpful for understanding the correlation between different topological states and their relationship with magnetic properties of a material, and also it will definitely contribute to the applications in various fields of magnetic materials. © 2015 Chinese Physical Society.

Jiang H.-X.,CAS Shenyang Institute of Metal Research | Zhao J.-Z.,CAS Shenyang Institute of Metal Research
Chinese Physics Letters | Year: 2012

Continuous solidification experiments are carried out with Al-Pb alloys under the effect of a direct current. The microstructure evolution in the samples is calculated. The numerical results obtained indicate that a direct current has great effects on the solidification of immiscible alloys. It mainly affects the microstructure evolution during a liquid-liquid decomposition by changing the spatial motions of the minority phase droplets and the temperature field in front of the solidification interface. A sample with either a well dispersed or a core/shell microstructure can be obtained by solidifying Al-Pb alloys under the effect of properly selected direct currents. © 2012 Chinese Physical Society and IOP Publishing Ltd.

Liu G.,CAS Shenyang Institute of Metal Research | Yu J.C.,Chinese University of Hong Kong | Lu G.Q.,University of Queensland | Cheng H.-M.,CAS Shenyang Institute of Metal Research
Chemical Communications | Year: 2011

Crystal facet engineering of semiconductors has become an important strategy for fine-tuning the physicochemical properties and thus optimizing the reactivity and selectivity of photocatalysts. In this review, we present the basic strategies for crystal facet engineering of photocatalysts and describe the recent advances in synthesizing faceted photocatalysts, in particular TiO2 crystals. The unique properties of faceted photocatalysts are discussed in relation to anisotropic corrosion, interaction dependence of adsorbates, photocatalytic selectivity, photo-reduction and oxidation sites, and photocatalytic reaction order. Ideas for future research on crystal facet engineering for improving the performance of photocatalysts are also proposed. © 2011 The Royal Society of Chemistry.

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.

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.

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.

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.

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.

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 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.

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.

Zhu Z.-D.,CAS Shenyang Institute of Metal Research | Ma E.,Johns Hopkins University | Xu J.,CAS Shenyang Institute of Metal Research
Intermetallics | Year: 2014

A major challenge for the structural applications of bulk metallic glasses (BMGs) is to improve their fracture toughness. Here we demonstrate that by increasing the cooling rate during the casting of liquid Cu49Hf 42Al9 into BMG, using a mixed argon and helium atmosphere, the notch toughness of the resultant BMG can be tripled relative to that obtained at slower cooling rates. The much elevated toughness is attributed to a ten-fold increase in the size of the plastic zone at crack tip, due to the proliferation of shear banding facilitated by enhanced propensity for shear transformations. The latter propensity is explained by the reduced shear modulus and microhardness, as well as increased enthalpy recovery, all of which are rooted in structural disorder as reflected by the lowered density and increased frozen-in excess volume. Such a structure-property correlation is systematically demonstrated by monitoring all these properties over a range of diameters of the as-cast BMG rods that correspond to cooling rate levels from 40 K/s to 103 K/s. © 2013 Elsevier Ltd. All rights reserved.

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.

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.

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.

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.

Qi W.,CAS Shenyang Institute of Metal Research | Su D.,CAS Shenyang Institute of Metal Research
ACS Catalysis | Year: 2014

Catalysis over carbon, especially nanocarbon, is an attractive topic in material science and chemical engineering fields due to its significant advantages compared with conventional metal or metal oxide catalysts. This paper summarizes the recent developments, basic concepts, and commonly accepted understandings on the nature of carbon catalysis in oxidative dehydrogenation reactions, including: introduction and comparison of various reaction systems; identity and quantity of active sites on carbon catalysts; mechanism for the reactions; and structure-selectivity relations for modified carbon catalysts. These fruitful conclusive achievements are the basis for in-depth comprehension of carbon-catalyzed oxidative dehydrogenation process at the molecular level, and many other efforts, such as detailed kinetic study, precisely controllable synthetic technique for nanocarbon catalysts, are still needed to further push carbon catalysis fields to practical applications. © 2014 American Chemical Society.

Niu Y.,CAS Shenyang Institute of Metal Research | Cui R.,PLA Air Force Aviation University | He Y.,PLA Air Force Aviation University | Yu Z.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2014

A novel kind of oxide film was successfully prepared on the Mg-Gd-Y-Zr alloy by mixed molten-salt bath treatment. The composition and microstructure of the film were studied by XRD and SEM. Wear and corrosion behavior of the modified surface film was evaluated. According to XRD and SEM analysis, it was confirmed that the oxide film resulted in uniform distribution of MgO phase. The implantation of MgO phase in the film is expected to harden the surface and retard the dissolution behavior greatly in NaCl solution, and acts as an artificial compact and continuous passive film with the thickness of tens of microns. © 2014 Elsevier B.V. All rights reserved.

Zhang Y.,Northeastern University China | Yang B.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2014

The magnetic properties and magnetocaloric effect (MCE) in ErNi 2-xFexB2C have been studied. Substitution of Fe for Ni lowered the magnetic transition temperature T M, and reduced the magnetic hysteresis of ErNi2B 2C. An inverse MCE was observed under low magnetic field and at low temperatures, which is attributed to the nature of antiferromagnetic state for the present ErNi2-xFexB2C compounds. A normal MCE was observed under higher magnetic field changes, which is related to a field-induced first order metamagnetic transition from antiferromagnetic to ferromagnetic state. The maximum values of magnetic entropy change -ΔSMmax are 14.5, 12.7, and 10.6 J/kg K with a magnetic field change of 0-70 kOe for x = 0, 0.1, and 0.2 in ErNi 2-xFexB2C, respectively. © 2014 Elsevier B.V. All rights reserved.

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.

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.

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.

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.

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.

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.

Ma X.,CAS Shenyang Institute of Metal Research | Li D.,CAS Shenyang Institute of Metal Research
International Journal of Heat and Mass Transfer | Year: 2016

The chemical heterogeneity, well-known as macrosegregation, is a major problem in the casting of steel ingots. Most heterogeneity generally originated from the solute partition and solute distribution in the solidification process with interdendritic convection. In this article, a new heterogeneous phenomenon originated from the movement of separate enriched melt is discovered in a steel ingot. A strip characterized as ferrite chains and MnS chains is revealed by macro-etching. The formation mechanism for the heterogeneous strip is proposed. In the mushy zone of the ingot, a large amount of separate S-enriched melts move laterally and upwards. Some S-enriched melts will remain in the moving trace. Such residual S-enriched melts produce a large amount of MnS inclusion chains. In the subsequent solid phase transition process, promoted by the MnS chains, ferrite prefers to be transited from the austenite near the MnS inclusions and shows as a large amount of separate ferrite chains. A large amount of ferrite chains align in a strip-like zone, which results in the heterogeneous strip phenomenon in macro-etching process. The physical model about the driving force for the movement of separate S-enriched melts is further theoretically analyzed. In the mushy zone, the interface tension resultant applied on the separate S-enriched melts can act as the drive force for the lateral movement of separate S-enriched melts. And the buoyance applied on the separate S-enriched melts acts as the drive force for the upwards movement. The interaction between the impurity movement and the solute segregation is also discussed. © 2016 Elsevier Ltd. All rights reserved.

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: 2010

A novel method to fabricate titanium aluminum carbides/alumina-laminated composites with weak interfaces was developed through heat treatment titanium aluminum carbides at 1300°C and low oxygen partial pressure. The laminated composites consist of 0.5-mm-thick layers of titanium aluminum carbides joined together by the in situ formed Al2O3 interlayers. The interfaces are free of cracks or delaminations. These laminated materials exhibit better damage tolerance compared with the monolithic counterparts. Crack deflection along the Al2O3 interlayers was the main mechanism for the noncatastrophic failure. The fracture toughness was increased from 4.9 MPa·m1/2 for Ti2AlC to 7.3 MPa·m1/2 for Ti2AlC/Al2O3 composite and from 6.5 MPa·m1/2 for Ti3AlC 2 to 10.4 MPa·m1/2 for Ti3AlC 2/Al2O3 composite, and the work of fracture required to break samples was increased from 153 J/m2 for Ti 2AlC to 676 J/m2 for Ti2AlC/Al 2O3 composite and from 300 J/m2 for Ti 3AlC2 to 1317 J/m2 for Ti3AlC 2/Al2O3 composite. © 2010 The American Ceramic Society.

Yuan B.,Xuzhou Normal University | Wang C.,Xuzhou Normal University | Wang C.,CAS Shenyang Institute of Metal Research | Li L.,Xuzhou Normal University | And 2 more authors.
Corrosion Science | Year: 2012

The anodic dissolution of copper in NaCl solutions with the application of an external magnetic field of 450. mT is studied by digital holography. The effects of the field on the basic electrochemical processes are visualized through reconstructed phase maps, which enable direct observation of the magnetohydrodynamic flow during the electrochemical mass transport. The magnetic field affects the anodic dissolution of copper in chloride media in two ways: restraining the formation of the CuCl salt layer, increasing the mass transport rate. The presentation of dynamic phase maps through the video enhances the power of digital holography in investigating electrochemical processes. © 2012 Elsevier Ltd.

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.

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.

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.

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.

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.

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.

Meschel S.V.,Illinois Institute of Technology | Meschel S.V.,James Franck Institute | Nash P.,Illinois Institute of Technology | Chen X.-Q.,CAS Shenyang Institute of Metal Research
Journal of Alloys and Compounds | Year: 2010

The standard enthalpies of formation of intermetallic compounds of some late 4d and 5d transition metals have been measured by high temperature, direct synthesis calorimetry at 1373 ± 2 K. The following results in kJ/mol of atoms are reported: NbMn2 (-10.4 ± 2.7); NbRu (-0.7 ± 2.8); RhMo (-4.8 ± 1.8); PdMn (-45.2 ± 2.2); Pd2Mo (-9.2 ± 1.9); TaMn2 (-14.5 ± 2.5); IrMn3 (-13.2 ± 2.8); Pt3Cr (-8.8 ± 3.1); PtMn (-53.6 ± 1.5); PtMo (-17.9 ± 2.2); Pt3Ta (-21.1 ± 2.4); and YMn2 (-2.8 ± 2.8). The values are compared with predicted values of Miedema and co-workers and with new results from ab initio calculations when available. We will present a systematic picture of how the enthalpies of formation may be related to the atomic number of the transition metal. We will also compare the thermochemical behavior of the Fe, Co, Ni group with the late transition metal alloys. © 2009 Elsevier B.V. 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.