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采用Gleeble-1500D热模拟机对Mg-8Li-2Al-1Zn合金进行热压缩实验,研究了变形温度为523~723 K、应变速率为0.01~10 s-1条件下的合金热变形行为,并建立了合金的流变应力本构方程及热加工图。结果表明:Mg-8Li-2Al-1Zn合金的流变曲线均属于动态再结晶型,流变应力随着温度升高(应变速率降低)而减小。显微组织的变化验证了动态回复和动态再结晶的发生。Mg-8Li-2Al-1Zn合金流变应力本构关系可以用双曲正弦函数和Z参数准确的描述,平均应力指数为4.62,平均热激活能为139.35 J/mol。根据建立的加工图,预测合金热变形的最佳工艺参数为:523~573 K,0.1~1 s-1。
The hot compression behavior of Mg-8Li-2Al-1Zn alloy was investigated by Gleeble-1500D thermal simulator. The hot deformation behavior of the alloy was studied under the condition of deformation temperature of 523-723 K and strain rate of 0.01-10 s-1, The flow stress constitutive equation and the hot working diagram of the alloy. The results show that the rheological curves of Mg-8Li-2Al-1Zn alloy belong to the dynamic recrystallization type, and the flow stress decreases with the increase of temperature (the strain rate decreases). Changes in microstructure verified the dynamic response and dynamic recrystallization. The constitutive relation of flow stress of Mg-8Li-2Al-1Zn alloy can be accurately described by hyperbolic sine function and Z parameter with an average stress index of 4.62 and an average thermal activation energy of 139.35 J / mol. According to the established processing diagram, the optimum technological parameters for predicting the thermal deformation of the alloy are: 523-573 K, 0.1-1 s-1.