Mg-8Gd-(0,3)Sm-0.5Zr合金的动态再结晶生长动力学

Dynamic recrystallization growth kinetics of Mg-8Gd-(0,3)Sm-0.5Zr alloys

利用铸造法制备了Mg-8Gd-(0,3)Sm-0.5Zr合金,并进行了525℃均匀化处理8 h,随后在温度为350~500℃及应变速率为0.002~1 s^(-1)的条件下进行热压缩试验,绘制并分析合金热压缩后的真应力-真应变曲线,构建其动态再结晶生长动力学双参数模型,并分析了合金生长动力学曲线特点及显微组织特征。结果表明:两种合金在热压缩时均发生了动态再结晶,通过双参数模型绘制动态再结晶动力学曲线,发现在高温低应变速率热压缩时,在真应变约0.2时,合金的动态再结晶的体积分数迅速增加至90%以上。对比分析Sm元素添加后的动态再结晶动力学曲线,发现Sm元素促进动态再结晶的进行,尤其在高温低应变速率热压缩时,在变形初期Sm的促进作用更明显。

Mg-8Gd-(0,3)Sm-0.5Zr alloys were prepared by casting method and homogenized at 525℃for 8 h,and then hot compression tests were conducted at temperatures ranging from 350℃to 500℃and strain rates ranging from 0.002 s-1 to 1 s^(-1).The true stress-strain curves of the alloy after hot compression were plotted and analyzed,and a dynamic recrystallization growth kinetics dual parameter model was constructed.The characteristics of growth kinetics curve and microstructure of the alloy were analyzed.The results show that dynamic recrystallization occurs in both alloys during hot compression.The dynamic recrystallization kinetics curves are plotted using a dual parameter model,and it is found that the volume fraction of dynamic recrystallization in the alloy rapidly increases to more than 90%at a true strain of about 0.2 during high temperature and low strain rate hot compression.By comparing and analyzing the dynamic recrystallization kinetics curves of the alloy after the addition of Sm element,it is found that Sm element promotes the progress of dynamic recrystallization,especially during high temperature and low strain rate hot compression,the promoting effect of Sm is more obvious in the early stage of deformation.