LZ61镁锂合金热变形行为研究

Thermal Deformation Behavior of LZ61 Mg-Li Alloy

采用热压缩变形的方法对锻态LZ61镁锂合金的热变形行为进行研究,分析了应变速率对其热变形行为的影响及其微观组织演变规律。结果表明,合金的流变曲线呈现动态再结晶特征,流变应力随应变速率降低而减少;研究范围内合金的应变速率敏感指数为0.283,接近准超塑性。锻态合金组织由α-Mg相基体及其晶界上的弥散分布的β-Li相组成,经热压缩后,显微组织的变化证明了动态回复和动态再结晶的发生;热压缩过程中该合金的主要塑性变形机制为晶界滑移。

A thermal compression deformation experiment was performed for investigating the thermal deformation behavior of as-cast LZ61 Mg-Li alloy,and the influence of strain rate on the thermal deformation behavior and its microstructure evolution were also analyzed.The results show that the rheological curve of the alloy presents to be a dynamic recrystallization process and the rheological stress decreases with the decrease of strain rate.The strain rate sensitivity index of the alloy in the research is 0.283,close to the quasi-superplasticity.The microstructure of as-cast alloy is composed ofα-Mg phase matrix andβ-Li phase that is dispersed on the grain boundary.After thermal compression,the variation in the microstructure proves the occurrence of dynamic recovery and dynamic recrystallization.Grain boundary sliding is the main plastic deformation mechanism for this alloy during thermal compression.