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Huang Y.,Jinling Institute of Technology | Yuan G.,Nanjing University of Science and Technology | Yuan G.,Jiangsu Institute of Advanced Materials
Materials Letters | Year: 2012

Vertical one-dimensional ZnO nanorods were synthesized on Cu substrate at a low temperature of 450 °C through vapor phase transport method. The growth of nanorods should be consistent with the Stranski-Krastanov (SK) island growth mode. The field emission (FE) properties were tested, and the turn-on field of FE was about 2.3 V/μm at the current density of 10 μA/cm 2. Meanwhile, the emission current densities reached 1 mA/cm 2 at a bias field of 4.2 V/μm. The field enhancement factor β was estimated to be about 3200. The variation of emission current density was less than 5% during a 12-hour test under a field of 4.2 V/μm, which suggests the good FE stability of ZnO nanorods. © 2012 Elsevier B.V. All rights reserved. Source


Luan J.H.,City University of Hong Kong | Jiao Z.B.,City University of Hong Kong | Chen G.,Nanjing University of Science and Technology | Chen G.,Jiangsu Institute of Advanced Materials | Liu C.T.,City University of Hong Kong
Journal of Alloys and Compounds | Year: 2014

The effects of B and Y on the mechanical properties and oxidation behavior of cast Ti-6Al-4V alloys were systematically investigated, and the new alloys with improved ductility and oxidation resistance are developed by the microalloying approach. The results indicate that boron is beneficial for improving the ductility by not only grain-size refinement but also grain-boundary enhancement, while yttrium is effective in increasing the oxidation resistance through possibly slowing down the oxidation kinetics. The improved properties, together with their high strength, make the microalloyed cast Ti-6Al-4V alloys competitive for practical engineering applications. © 2014 Elsevier B.V. All rights reserved. Source


Zhang X.L.,Nanjing University of Science and Technology | Zhang X.L.,Jiangsu Institute of Advanced Materials | Chen G.,Nanjing University of Science and Technology | Chen G.,Jiangsu Institute of Advanced Materials | Bauer T.,Nanjing University of Science and Technology
Intermetallics | Year: 2012

An in situ formed Mg 75Cu 13.33Y 6.67Zn 5 bulk metallic glass composite with both excellent high bio-corrosion resistance and superior mechanical properties has been synthesized. The composite shows a significant plastic strain of about 19% and high compressive strength of about 1040 MPa. Attributed to the glassy matrix that postpones the growth of corrosion pits, the composite displays high pitting potential and low corrosion current density. The corrosion current density is about two orders of magnitude lower than AZ31 alloy. The composite presents a uniform corrosion morphology with micro-scale uniformly distributed corrosion pits. Electrochemical impedance spectroscopy for composite alloy consists only of single capacitive loop. © 2012 Elsevier Ltd. All rights reserved. Source


Chen G.,Nanjing University of Science and Technology | Chen G.,Jiangsu Institute of Advanced Materials | Cheng J.L.,Nanjing University of Science and Technology | Cheng J.L.,Jiangsu Institute of Advanced Materials | Liu C.T.,City University of Hong Kong
Intermetallics | Year: 2012

A large-sized Zr-based BMG composite containing coarse and spherical β-Zr precipitates was produced using the semi-solid progressive solidification (SSPS) method. Specimens with a 6-mm-diameter gauge section fabricated from 11-mm-diameter cast rods, which are at least twice larger than those reported previously, have been used for mechanical-property evaluation. Our results show that the composite exhibits both excellent work hardening and plasticity. Both the microstructure evolution as a function of isothermal temperature & holding time and its influence on the mechanical properties were investigated. The mechanical properties of the composite are found to be closely related to microstructural features, and the tensile plasticity can be enhanced significantly with increasing the size scale of β-Zr precipitates. It's evidenced that β-Zr precipitates yield firstly and the plastic deformation with a significant work hardening follows as the stress exceeds the maximum elastic stress. Shear bands are found to be essentially nucleated at the interface between the β-Zr particle and the glassy matrix. With further loading, the strain softening induced by the plastic deformation of the glass matrix increases. When the capacity of the strain softening by the matrix offsets the contribution of the work-hardening by the β-Zr precipitates, the stress will reach the maximum value and then the necking occurs. The mechanistic understanding of the deformation mechanism in the large-sized BMG composite sheds light on the design of BMG composites with enhanced mechanical properties. © 2012 Elsevier Ltd. All rights reserved. Source


Chen G.,Nanjing University of Science and Technology | Chen G.,Jiangsu Institute of Advanced Materials | Zhang X.L.,Nanjing University of Science and Technology | Zhang X.L.,Jiangsu Institute of Advanced Materials | Liu C.T.,City University of Hong Kong
Scripta Materialia | Year: 2013

This paper reports the design and synthesis of the in situ intermetallic-phase reinforced amorphous-matrix composite (Mg 65Cu 10Ni 10Y 10Zn 5) 91Zr 9. In situ formed intermetallic ZrNi particles significantly improve the mechanical properties of the composite. The composite shows a compressive strength as high as 1039 MPa, and its ductility is substantially higher than that of the monolithic metallic glass. The mechanism governing the formation of the intermetallic phase and the beneficial effect of the hard intermetallic particles on the deformation and fracture of the composite is discussed. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

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