Papers by Keyword: Mg-Y-Zn Alloy

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Authors: Bin Chen, Dong Liang Lin, Xiao Qin Zeng, Chen Lu
Abstract: The elevated temperature mechanical behavior of Mg-Y-Zn alloys was investigated. It was found that the extruded Mg-Y-Zn alloy exhibited excellent mechanical properties both at ambient temperature and elevated temperature. With the increase of tensile temperature, the ultimate tensile strengths of Mg-Y-Zn alloys decreased and their elongations increased. The ultimate tensile strengths increased and elongations decreased with the increase of yttrium content. However, a gradual increase in the ultimate tensile strength and elongation both at ambient temperature and elevated temperature was obtained by increasing both yttrium and zinc contents. The fracture modes of Mg-Y-Zn alloys at different tensile temperature were also investigated.
237
Authors: Taiki Morishige, Masato Tsujikawa, Sachio Oki, M. Kamita, Sung Wook Chung, Kenji Higashi
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Authors: Shu Lin Lü, Xiong Yang, Shu Sen Wu, Xiao Gang Fang, Jing Wang
Abstract: The long period stacking ordered (LPSO) phase reinforced Mg alloys have received many researches in recent years because of their excellent mechanical properties. However, the LPSO phase usually concentrates at the grain boundaries with a coarse network structure, which seriously deteriorates its strengthening effect. In this research, rheocasting and ultrasonic vibration (USV) process were firstly used to refine the LPSO phase in Mg alloy. The semisolid slurry of Mg96.9Y2Zn1Zr0.1 (at.%) alloy was prepared by USV and then formed by rheo-squeeze casting (RSC). The effects of USV and squeeze pressure on the microstructure and mechanical properties of this Mg alloy were investigated. The results show that the primary α-Mg and coarse LPSO phases were refined obviously by USV and RSC. The tensile strength and elongation of the RSC Mg96.9Y2Zn1Zr0.1 alloy were 232 MPa and 17.7% respectively, which were increased by 17.8% and 172.3% respectively compared to the conventional liquid casting alloy. The refinement mechanism of the LPSO phase in semisolid Mg alloy is also discussed.
186
Authors: Taiki Morishige, Masato Tsujikawa, Sung Wook Chung, Sachio Oki, Kenji Higashi
Abstract: Friction stir processing (FSP) is the effective method of the grain refinement for light metals. The aim of this study is to acquire the fine grained bulk Mg-Y-Zn alloy by ingot metallurgy route much lower in cost. Such bulk alloy can be formed by the superplastic forging. The microstructure of as-cast Mg-Y-Zn alloy was dendrite. The dendrite arm spacing was 72.5 [(m], and there are the lamellar structures in it. FSP was conducted on allover the plate of Mg-Y-Zn alloy for both surfaces by the rotational tool with FSW machine. The stirring passes were shifted half of the probe diameter every execution. The dendrite structures disappeared after FSP, but the lamellar structure could be observed by TEM. The matrix became recrystallized fine grain, and interdendritic second phase particles were dispersed in the grain boundaries. By using FSP, cast Mg-Y-Zn alloy could have fine-grained. This result compared to this material produced by equal channel angular extrusion (ECAE) or rapid-solidified powder metallurgy (RS P/M). As the result, as-FSPed material has the higher hardness than materials produced by the other processes at the similar grain size.
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