Papers by Author: Wei Dong Fei

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Authors: Bo Wen Zhang, Yong Da Yan, Zhen Jiang Hu, Xue Sen Zhao, Ying Chun Liang, Wei Dong Fei, Shen Dong
Abstract: As the dimensions of parts become smaller, understanding the mechanical properties of these small components was becoming more important. Till present day, the methods and technology used to investigate the deformation behavior in nanoscale were still lacking. In this paper, the specimens were single crystal copper wires with diameter in 50 microns. Atomic force microscope integrated with an in- situ tensile system were used to determine the mechanical behavior of copper wires and observe the surface topography deformation in nanoscale simultaneously. The results were as follows: the modulus of elasticity, tensile strength and failure strain of the sample were 167Gpa, 0.564GPa and 0.011, respectively. By using AFM, the separation process between the copper wire and impurities on it, such as oxide film, was observed. The nanoscale deformation process of the copper wire was also obtained.
Authors: Pei Tang Zhao, Zhi Ming Du, Li Dong Wang, Wei Dong Fei
Abstract: The 6061Al matrix composites reinforced with SnO2-coated aluminum borate whisker were fabricated using squeeze casting method. The composites with different SnO2 coating contents were extruded successfully at 350°C with the extrusion rate of 18mm/s. The results show that the Sn particles at the interface as liquid state at extrusion temperature result in the reduction of the extrusion load and the decrease of the probability of whisker fracture during hot deformation process. Moreover, unlike many surface cracks can be seen in the extruded composite without whisker coating, the surface crack-free extruded rods can be obtained for composites with whisker coating. The ABOW/SnO/6061Al composites tensile properties increased obviously after extrusion.
Authors: Pei Lian Wu, Chen Yi Yao, Li Dong Wang, Wei Dong Fei
Abstract: Magnesium borate whisker reinforced aluminum alloy 2024 (AA2024) composite was fabricated by squeeze casting method, after was CuO coating of the whisker. The interfacial reaction in the composite was investigated. To change the interfacial reaction degree, the solution treatment for different time was carried out. The results show that the interfacial reaction degree increases with solution time increasing. The maximum ultimate tensile strength can be obtained when the solution time is suitable.
Authors: Gang Li, Wei Dong Fei
Abstract: The thermal expansion behaviors of aluminum borate whisker and Fe3O4 reinforced pure aluminum matrix composite with different thermal treatments were studied. Using transmission electron microscopy (TEM) the microstructures of the composite were investigated. The results indicated that the thermal expansion coefficient of the new composite was low. It can be found that the thermal expansion coefficient of as-cast composite is much lower than that of quenched and annealed composites. On the basis of phase transformation analysis of Fe3O4 particles in the composite, the mechanism of low CTE of the composite was discussed.
Authors: Rajabtabar Darvishi Ali, Wei Li Li, Sheikhnejad Bishe Ommeaymen, Li Dong Wang, Zhe Liu, Wei Dong Fei
Abstract: Pb(Zr0.52Ti0.48)O3 was coated on the surface of CaCu3Ti4O12 particles that prepared using sol-gel method. Then the composite particles were sintered into composite ceramics using cold press with the two different pressures and pressing time to achieve sufficient higher relative density after sintering. Afterward, the composite particles were sintered into composite ceramics with various sintering time at the same temperature to reach smaller grain size and higher relative density. The results show that the ceramics are composed of Pb(Zr0.52Ti0.48)O3 and CaCu3Ti4O12 phases, and Pb(Zr0.52Ti0.48)O3 phase is mainly exist at the grain boundary even the composite particles sintered for 2h before pellet making. The results exhibit when density of CaCu3Ti4O12/Pb(Zr0.52Ti0.48)O3 composite ceramic is kept in higher level using this simple technology, not only The dissipation loss in these giant-dielectric constant materials was reduced to a considerable level of practical applications but also dielectric constant enhance to very high level in the large frequency range. The results show that the improvement of the dielectric loss and dielectric constant enhancing mainly comes from the increase in the density of the CaCu3Ti4O12/Pb(Zr0.52Ti0.48)O3 composite ceramics using suitable pressure in cold press, suitable short sintering time that lead to smaller grain size and sufficient grain boundary.
Authors: Zi Yue Yang, Li Dong Wang, Rui Xuan Song, Dong Xing Zhang, Wei Dong Fei
Abstract: Cu (In,Ga)Se2 (CIGS) thin films were prepared by direct magnetron sputtering CIGS quaternary target at the substrate temperature varying from room temperature (RT) to 300 °C. The effects of substrate temperature on the structural and electrical properties of CIGS films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Hall effect measurement. The CIGS thin films with a chalcopyrite structure were obtained between 100 and 300 °C and the crystallinity of films were enhanced with the increase of the substrate temperature from 100 to 300 °C. The film compositions were consisted with the target when the substrate temperatures were between RT and 200 °C, however, it deviated from the stoichiometry of the target when the substrate temperature was 300 °C. The CIGS films deposited at 200 °C had the higher carrier mobility of 3.522 cm2/Vs.
Authors: Zhi Ming Du, Pei Tang Zhao, Li Dong Wang, Wei Dong Fei
Abstract: The 6061Al matrix composites reinforced with SnO2-coated aluminum borate whisker were fabricated using squeeze casting method. The composite were extruded successfully at 350°Cwith different die angles. The experiment results illustrate that the die angle have important influences on the extrusion process. The surface quality of extruded composites was improved and the extrusion load was reduced with die angle increasing from 30 to 60 degree. The <111> and <100> textures for aluminum matrix were formed in all extruded composites. The dispersion degree of the <111> texture, the alignment degree and the average length of whiskers increases with die angle increasing. There is a suitable die angle for the optimization of the extrusion process of the present composite.
Authors: Wei Dong Fei, Zhi Jun Li, Hong Yan Yue, Li Dong Wang
Abstract: Extrusion experiments have been carried out on Bi2O3-coated Al18B4O33 whisker reinforced aluminum matrix composite. The effects of the extrusion temperature on the microstructures, the formability and the mechanical properties of ABOw reinforced aluminum (ABOw/Al) composites with and without Bi2O3 coating were investigated. The results show that the steady-state extrusion load and the probability of whisker fracture of the extruded two composites decrease with the extrusion temperature increasing. The mechanical properties of the composites attain highest values at extrusion temperature of 673K.
Authors: Pei Lian Wu, Li Dong Wang, Wei Dong Fei
Abstract: In the present study, MBOw/Al composites were fabricated using squeeze casting method. The interfacial reaction in the composite was investigated using transmission electron microscope (TEM). The tensile properties of the composites with different kinds of matrix were studied. The experimental results showed that the properties of the composite were very good.
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