稀土Er对ZK60镁合金变形行为的影响

采用Gleeble-1500D热模拟试验机研究了稀土元素Er对ZK60镁合金的热压缩变形行为的影响。通过引入Zener-Hollomon参数和双曲正弦函数构建了ZK60和ZK60-1.0Er镁合金的本构方程,同时采用应变硬化率θ-流变应力σ关系曲线确定动态再结晶发生的临界应力σc值。结果表明:ZK60和ZK60-1.0Er两种镁合金在热压缩变形过程中,随着变形温度T的升高,压缩流变应力σ值均减小;随着应变速率ε?的增加,流变应力σ值均增加。添加稀土元素Er使得ZK60镁合金热压缩变形流变应力σ值和应力指数n值增加,在变形温度为160~320℃时提高了发生动态再结晶的临界应力σc值,稀土相的存在促进了再结晶晶粒的形核,降低了平均变形激活能Qˉ值。

Effect of erbium on thermal compression deformation behavior of ZK60 magnesium alloy

The effect of rare earth element erbium on the thermal compression deformation behavior of the ZK60 magnesium alloy was studied by Gleeble-1500D thermal simulator. Constitutive equation of thermal compression of ZK60 and ZK60-1.0Er magnesium alloy was developed by the Zener-Hollomon parameter and the hyperbolic sine function. Meanwhile,the critical stress value of dynamic recrystallization was determined by the curve of strain hardening rate and stress. The results show that:in the process of hot compression defor-mation of the ZK60 and ZK60-1.0Er magnesium alloys,the flow stress decreases with the increase of deforma-tion temperature;the flow stress increases with the increase of strain rate. By adding rare earth Er,the flow stress and stress exponent increased,the critical stress value of dynamic recrystallization within 160~320℃increased as well. The existence of rare earth phase promoted the formation of the recrystallization grain nucle-ation due to the reduces of the average deformation activation energy Qˉ.