(中南大学 材料科学与工程学院， 长沙 410083)
摘 要: 采用GLEEBLE-1500热模拟机对Mg-Gd-Y-Zr稀土镁合金在温度为300~500 ℃、 应变速率为0.000 1~1.0 s-1、最大变形程度为50%的条件下， 进行了恒应变速率高温压缩模拟实验研究， 分析了实验合金高温变形时流变应力与应变速率及变形温度之间的关系以及组织变化，计算了塑性变形表观激活能及相应的应力指数， 为选择这种合金的热变形加工条件提供实验依据。 结果表明： 合金的稳态流变应力随应变速率的增大而增大, 在恒应变速率条件下， 合金的真应力水平随温度的升高而降低； 在给定的变形条件下， 计算得出的塑性变形表观激活能和应力指数分别为260 kJ/mol和5.6。 根据实验分析， 合金的热加工宜在400~500 ℃温度范围内进行。
关键字: 稀土镁合金； 热变形； 变形激活能； 力学性能
（School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: The stress-strain relation of Mg-8.75%Gd-3.82%Y-0.54%Zr (mass fraction,%) alloy was investigated. The test was carried out in the strain rate range of 0.000 1-1.0 s-1, in the temperature range of 300-500 ℃ and at maximum strain of 50% on hot-simulation machine GLEEBLE-1500. The relation between true stress, true strain and that between deformation temperature and microstructures of the tested alloy were studied during hot-compression. The apparent deformation activation energy and corresponding stress exponent under hot-compression evaluated quantitatively. The results may lay the foundation for selecting hot deformation conditions of the alloy. The relation between stress and strain is obviously affected by strain rate and deformation temperature. The steady flow stress becomes higher with increase of strain rate at constant temperature, and lowers with increase of deformation temperature at constant strain rate. The apparent deformation activation energy increases markedly in the range of 400-500 ℃, no more changes in the range of 300-400 ℃. The apparent activation energy 260 kJ/mol and the corresponding stress exponent 5.6 were determined respectively. The temperature range of 400-500 ℃ is suggested for hot deformation of this alloy.
Key words: rare earth magnesium alloy; hot deformation; deformation activation energy; mechanical properties
