中文摘要：

利用金相显微镜和图像分析设备对等径道角挤压预变形AZ61镁合金在半固态等温处理中的微观组织演变进行研究。先利用等径道角挤压对AZ61镁合金铸坯在310℃进行应变诱导,然后将其在半固态进行不同时间的等温处理。研究结果表明：挤压道次、等温处理温度和变形路径影响预变形AZ61镁合金在半固态等温处理中的微观组织演变过程。在将等温处理温度从530℃升高至560℃的过程中,合金的平均晶粒尺寸从22μm增大到35μm。当等温处理温度为575℃时,平均晶粒尺寸减小。当等径道角挤压的变形路径为BC时,预变形AZ61镁合金在半固态等温处理中获得的微观组织晶粒尺寸最小。

英文摘要：

The microstructural evolution of AZ61 magnesium alloy predeformed by equal channel angular extrusion（ECAE） during semisolid isothermal treatment（SSIT） was investigated by means of optical metalloscopy and image analysis equipment.The process involved application of ECAE to as-cast alloy at 310 ℃ to induce strain prior to heating in the semisolid region for different time lengths.The results show that extrusion pass,isothermal temperature and processing route have an influence on microstructural evolution of predeformed AZ61 magnesium alloy during SSIT.With the increase of extrusion pass,the solid particle size is reduced gradually.When isothermal temperature increases from 530 ℃ to 560 ℃,the average particle size increases from 22 μm to 35 μm.When isothermal temperature is 575 ℃,the average particle size decreases.The particle size of microstructure of AZ61 magnesium alloy predeformed by ECAE at BC during SSIT is the finest.