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在温度423~573 K和应变速率为0.001~1 s-1下,通过Gleeble-3500热机械试验机对双相Mg-9Li-3Al-2Sr合金进行等温热压缩实验,研究其热变形行为并评估其可加工性能。塑性失稳以锯齿形流变的形式存在,锯齿屈服效应归因于Mg和Li原子对移动位错的锁定作用。分析流变应力、应变速率和变形温度的关系,并通过Arrhenius公式计算得到不同应变条件下变形激活能和基本的材料参数。温度和变形速率对合金变形行为的影响可以用Zener–Hollomon指数函数来表示。通过比较不同变形条件下的预测值与实验流变曲线,来验证本构方程的合理性。经计算,得到其相关系数为0.9970,平均相对误差为4.41%。结果表明,该本构模型可以准确地预测双相Mg-9Li-3Al-2Sr合金的高温变形流动行为。
Under the temperature of 423-573 K and the strain rate of 0.001-1 s-1, the isothermal hot compression tests of the two-phase Mg-9Li-3Al-2Sr alloy were carried out by Gleeble-3500 thermo-mechanical testing machine, Evaluate its machinability. The plastic instability exists in the form of zigzag rheology. The serrated yielding effect is attributed to the locking effect of Mg and Li atoms on the mobile dislocations. The relationship between flow stress, strain rate and deformation temperature was analyzed. The deformation activation energy and basic material parameters under different strain conditions were calculated by Arrhenius formula. The effect of temperature and deformation rate on the deformation behavior of the alloy can be expressed by the Zener-Hollomon exponential function. The rationality of the constitutive equation is verified by comparing the predicted values with the experimental rheological curves under different deformation conditions. After calculation, the correlation coefficient was 0.9970, the average relative error was 4.41%. The results show that this constitutive model can accurately predict the high temperature deformation flow behavior of Mg-9Li-3Al-2Sr alloys.