(哈尔滨工业大学 材料科学与工程学院， 哈尔滨 150001)
摘 要: 通过半固态重熔实验， 并利用金相显微镜，对等径道角挤压AZ91D镁合金的半固态组织演变进行了研究。结果表明： 等径道角挤压后二次加热等温处理是一种适于AZ91D镁合金的制坯方法，加热温度对坯料的组织有很大影响。 当保温时间一定时， 随着加热温度的升高， 先是球化效果越来越好， 后来发生晶粒合并长大现象， 晶粒尺寸也会逐渐长大， 当保温时间为15min， 加热温度为560℃时， 二次加热组织最好； 当加热温度一定时，随着保温时间的延长， 晶粒尺寸有长大的趋势， 当加热温度为560℃，保温时间为15min时组织球化效果最好，晶粒最细小； 当加热温度和保温时间一定时， 随着挤压次数的增加， 二次加热组织的晶粒尺寸减小。
关键字: AZ91D镁合金；半固态； 坯料； 二次加热组织
（ School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001, China）
Abstract: By means of reheating experiments and metalloscope, microstructure evolution of AZ91D magnesium alloy extruded by an equal channel angular die is investigated in semi-solid state. The results show that reheating the AZ91D magnesium alloy extruded by an equal channel die is a kind of good method of preparing AZ91D magnesium alloy billets. The remelted temperature has strong influence on the reheating microstructure. When holding time is constant, with the increment of remelted temperature, globular effect become good firstly, then crystal grains become large. When holding time is 15min, microstructure of remelted temperature of 560℃ is the best. When the remelted temperature is constant, with the increment of holding time, the crystal grain becomes large. When remelted temperature is 560℃, microstructure of holding time of 15min is the best. When remelted temperature and holding time are constant, with the increment of number times of extrusion the crystal grain becomes small.
Key words: AZ91D magnesium alloy; semi-solid; billets; reheated microstructure
