铸造Mg-4Al-2Sn-Y-Nd镁合金的热压缩行为与加工图

利用热压缩实验研究一种新型的具有优异室温塑性的Mg-4Al-2Sn-Y-Nd镁合金的高温流变行为，变形温度为200～400℃，应变速率为1.5×10-3～7.5 s^-1。结果表明：合金的应变速率敏感因子（m）在不同变形温度下均明显小于AZ31镁合金的m值，因此该合金适合在高应变速率下进行热加工。在真应力-应变曲线基础上，建立Mg-4Al-2Sn-Y-Nd 镁合金高温变形的本构方程，并计算得到合金的应力指数为10.33，表明合金在高温下主要的变形机制为位错攀移机制。同时，利用加工图技术确定合金的最佳高温变形加工窗口，即变形温度在350～400℃之间，应变速率在0.01～0.03 s^-1。

Hot compression behavior and processing map of cast Mg-4A1-2Sn-Y-Nd alloy

The plastic flow behavior of a newly developed high ductility magnesium alloy, Mg-4Al-2Sn-Y-Nd, was investigated by hot compression from 200 to 400 ℃ with a strain rate of 1.5×10-3 to 7.5 s-1. The results reveal that the strain rate sensitivity factor （m） of the alloy is much lower than that of the AZ31 alloy, which implies that the alloy should be more suitable for processing at high strain rate. The constitutive relationship of the alloy deformed at elevated temperature was obtained by plotting the experimental data. The stress exponent of the alloy is 10.33, which reveals that climb-controlled dislocations creep is the dominated deformation mechanism. The processing-map technique was used to determine the practical processing window. The proper deformation temperature and strain rate of the cast alloy were determined as 350-400 ℃ and 0.01-0.03 s-1, respectively.