Mg-Gd-Y-Zr合金热压缩变形组织及塑性失稳判据

Microstructure and plastic instability criteria of Mg-Gd-Y-Zr alloy during hot compression

采用Geeble-1500热模拟实验机对Mg-6Gd-3Y-0.5Zr合金进行热压缩实验,设定变形温度为623-773 K、变形速率为0.001-1 s^-1、最大真应变为0.6,利用指数函数关系计算合金的表观激活能,并建立合金的表观激活能图。根据动态材料模型（DMM）计算该合金的加工图,综合分析合金的表观激活能图、加工图以及m、m、S和S这4个判据得到：在723 K、0.01 s^-1以及773 K、0.1 s^-1的条件下,该合金能够获得稳定的塑性变形,并确定为该合金的最佳变形工艺。结合表观激活能图、加工图以及m、m、S和S这4个判据,能够更加准确地判断合金塑性失稳的工艺范围。

The hot compression tests were performed on Mg-6Gd-3Y-0.5Zr alloy at the deformation temperatures of 623-773 K, strain rates of 0.001-1 s^-1 and the maximum true strain of 0.6 by using Geeble-1500 test machine. The apparent activate energy was calculated according to exponential function, and the apparent activate energy map was established. The processing map was obtained according to dynamic materials model （DMM）. The optimum deformation conditions when the alloy can obtain the stable plastic deformation are obtained at condition of 723 K, 0.01 s^-1 and 773 K, 0.1 s^-1 by analyzing the apparent activate energy map, processing map and four criteria of m,m^· , S and S^ ·systematically. A more accurate range of the conditions for instable deformation can be determined by analyzing the apparent activate energy map, processing map and four criteria.