Authors: Qiang Li, Qu Dong Wang, Xiao Qing Zeng, Wen Jiang Ding, Quanbo Tang, Shao Dong Huang
Abstract: Nd, Y and Ca containing Mg-Zn-Zr alloys are produced by electromagnetic direct-chilling casting process, and extruded at a temperature of 643K with two extrusion ratios of 38:1 and 22:1, respectively. The grain size is markedly reduced from 80µm in as-cast alloy to 2~5µm in as-extruded alloy due to dynamic recrystallization, and lamellar eutectics at grain boundaries in as-cast alloy are broken up and fine precipitates in the matrix come forth during hot extrusions. Mechanical properties
of the alloys are measured by tensile test from room temperature to 523K. Nd, Y and Ca are favorable to the strength of the hot-extruded alloy, especially the elevated-temperature strength, which is above 200MPa in ultimate tensile strength at 523K.
385
Authors: Ming Yi Zheng, Xiao Guang Qiao, Shi Wei Xu, Kun Wu, Shigeharu Kamado, Yo Kojima
Abstract: Equal channel angular extrusion (ECAE) was applied to an extruded ZW1101 (Mg - 11wt%Zn - 0.9wt%Y) Mg alloy containing quasicrystallines. The as-extruded ZW1101 alloy had an initial grain size of about 12 µm and bands of quasicrystalline phases parallel to the extrusion direction. After the extruded alloy was subjected to ECAE processing, the grain size was refined to about 0.5 µm, and the quasicrystalline phases were further broken and dispersed in the matrix. After
the ECAE processing, the micro-hardness and yield strength of the alloy were increased, however, the ultimate tensile strength and the ductility of the alloy were slightly decreased.
589
Authors: Ming Yi Zheng, L.B. Tong, S.W. Xu, X.S. Hu, K. Wu, S. Kamado
Abstract: The as-cast Mg - 5.25 wt.% Zn - 0.6 wt.% Ca alloy was extruded at different extrusion temperatures (270, 300, and 330 °C). The extrusion temperature has a significant effect on the grain size, texture and mechanical properties of the Mg-Zn-Ca alloy. Upon extrusion, the as-cast coarse grains underwent pronounced grain refinement and the second phases were broken up and formed stringers in the extrusion direction. With the decreasing extrusion temperature to 270 °C, the grain size of the alloy was refined to about 1.5 μm, basal texture became stronger, which led to the higher tensile strength and moderate elongation to failure.
703
Authors: Xian Lan Liu, Chu Ming Liu, Wen Yu Zhang, Hui Zhong Li, Su Min Zeng
Abstract: Mcrostructure and properties of Mg-Zn-Nd-Cd-Zr alloy have been investigated on different solution treatments and artificial aging conditions by optical microscope, SEM (scanning electron microscope) and TEM(transmission electron microscope). The results indicate that the grain boundarys become thinner and the second phases distributed on the grain boundarys become finer by double-stage homogenization at 400°C for 2h plus 460°C for 12h than that of homogenization at 420°C for 24h. Double-stage homogenization brings a greater peak-ageing hardness and longer time to reach peak hardness 20h about., and the ultimate tensile strength is 345MPa at 140°C for 34h, higher 15% than that of as-extruded
76
Authors: Bin Liu, Jing Huai Zhang, Zhong Yi Niu, Jun Qing Li
Abstract: The as-cast Mg-14Li-3Al-(0-0.9)RE alloys were prepared with vacuum melting method, then processed by hot extrusion. The microstructure and tensile properties were investigated. The results show that both addition of RE and extrusion deformation can refine the grain size. Al3La compounds are formed with addition of La-rich misch metal. The as-extruded Mg-14Li-3Al-0.6RE alloy obtains the finest grain size (4.28 μm) and the highest mechanical properties (σb =222.75 MPa, δ=23.8%), which is related to the grain refinement and the formation of Al3La.
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