曹富荣管仁国丁桦李英龙周舸崔建忠
金属学报
doi:10.3724/SP.J.1037.2009.00582
采用熔铸和大变形轧制制备了Mg-6Li-3Zn合金板材, 研究了合金的高温变形行为、显微组织、空洞与位错蠕变机制. 在623 K和1.67×10-3 s-1条件下获得了300%的最大延伸率. OM, TEM和SEM观察显示, 合金带状晶粒组织在573 K和1.67×10-3 s-1条件下发生显著的动态再结晶, 亚晶轮廓不清晰,位错分布比较均匀. 合金在573-623 K和1.67×10-3 s-1条件下断裂形式为韧性断裂. 获得了新型的位错黏性滑移与位错攀移转变蠕变机制图,表明Mg-6Li-3Zn合金带状晶粒组织在573 K和1.67×10-3 s-1条件下高温变形机制为晶格扩散控制的位错黏性滑移, 其应力指数为3(应变速率敏感性指数0.33), 变形激活能为134.8 kJ/mol, 与Mg的晶格扩散激活能相同.获得了新型的考虑聚合的空洞长大图, 合金在573 K和1.67×10-3 s-1条件下的空洞长大机制为塑性控制的空洞长大.
关键词:
Mg-Li-Zn合金
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dislocation creep
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quasi-superplasticity
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mechanical property
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cavity
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金属学报(英文版)
Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys' formality, while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength (UTS) and yield strength (YS) of the alloy with 1wt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3 phase worsens the elongation.
关键词:
calcium
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