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Huang A.,Huazhong University of Science and Technology | Hu S.,Huazhong University of Science and Technology | Li Z.,Huazhong University of Science and Technology | Wang Y.,Beijing Hangxing Technology Development Co.
Applied Mechanics and Materials

To figure out the elements distribution in the seams, laser welding was carried out on the Al plates which coating with Si powder and Cu powder respectively, then electronic probe was used to analyze the microstructure in the section of the seams. Results indicated that alloying elements distribution in the weld is heterogeneous under the metal liquid movement in welding pool and the elemental diffusion co-functioning. There are two high concentration regions on both sides of the weld centerline, the content at the center is low, slightly higher and more homogeneous at the bottom. The distribution of the alloy composition in the weld is related to the specific gravity of the alloying elements. Though the specific gravity of Si and aluminum matrix is similar, it can flow with the liquid metal in the pool, so the concentration changes of Si in the weld are larger. Elemental fluctuation keeps steady in the weld joint. Source

Li D.,Tianjin University | Hu S.,Tianjin University | Shen J.,Tianjin University | Zhang H.,Tianjin University | Bu X.,Beijing Hangxing Technology Development Co.
Journal of Materials Engineering and Performance

Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α′ phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal. © 2016, ASM International. Source

Ma R.-X.,University of Science and Technology Beijing | Wang M.-K.,Beijing Hangxing Technology Development Co. | Kang B.,University of Science and Technology Beijing | Wang Y.-G.,University of Science and Technology Beijing
Optoelectronics Letters

Al and F co-doped ZnO (ZnO:(Al, F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents. The structural, electrical and optical properties of the deposited films are sensitive to the F doping content. The X-ray analysis shows that the films are c-axis orientated along the (002) plane with the grain size ranging from 9 nm to 13 nm. Micrographs obtained by the scanning electron microscope (SEM) show a uniform surface. The best films obtained have a resistivity of 2.16×10-3Ù.cm, while the high optical transmission is 92.0% at the F content of 2.46 wt.%. © Tianjin University of Technology and Springer-Verlag Berlin Heidelberg 2011. Source

Zhang H.,Tianjin University | Hu S.,Tianjin University | Shen J.,Tianjin University | Li D.,Tianjin University | Bu X.,Beijing Hangxing Technology Development Co.
Optics and Laser Technology

Abstract Laser beam welding was used to weld dissimilar joints in BTi-6431S/TA15 titanium alloys. The effect of laser beam offset on microstructural characterizations and mechanical properties of the joints were investigated. Microstructural evolution of the joints was characterized by optical microscopy (OM) and X-ray diffraction (XRD). Tensile testing was conducted at room temperature and at 550°C. The results demonstrated that with the exception of some porosity, a good quality joint could be achieved. Martensite α' and acicular α structures were present in the fusion zone (FZ). The amount of martensite α' present with the -0.2 mm beam offset was less than that with the 0.2 mm beam offset. Acicular α and martensite α' transformations occurred in the high temperature heat-affected zone (HT-HAZ) of both the BTi-6431S and TA15 alloys. In the low-temperature heat-affected zone (LT-HAZ), the BTi-6431S and TA15 alloy microstructures exhibited a mixture of secondary α, primary α, and prior β phases. The microhardness values in the FZ followed the order: -0.2 mm> 0 mm> 0.2 mm. Tensile testing at room temperature and at 550°C resulted in fracture of the TA15 alloy base metal. The fracture morphology exhibited a ductile dimple feature. © 2015 Elsevier Ltd. Source

Zhou T.,Northwestern Polytechnical University | Xiong Z.-Q.,Beijing Hangxing Technology Development Co. | Yao W.,Beijing Hangxing Technology Development Co. | Qin Y.,Beijing Hangxing Technology Development Co.
Tuijin Jishu/Journal of Propulsion Technology

In order to reduce the elastic deformation of thin-walled workpieces with poor rigidity, when it is under the clamping force of tooling during the manufacturing process, a method of flexible tooling layout optimization for the thin-walled workpieces based on the improved ant colony algorithm is presented. Tooling layout optimization of positioning/supporting array is realized by combining finite element analysis with ant colony-genetic hybrid algorithm. The verification of examples shows that the optimal state of the topological configuration and distribution density of positioning/supporting array in the flexible tooling system can be achieved through optimization by the improved genetic-ant colony algorithm, thus obtaining the optimal flexible tooling layout for the thin-walled workpieces. The maximum deformation of the thin-walled workpieces can be reduced by 47%. © 2016, Editorial Office of Journal of Propulsion Technology. All right reserved. Source

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