Mg-8Li-2Al-1Zn合金的热变形行为

Hot deformation behavior of Mg-8Li-2Al-1Zn alloy

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 deformation behavior of Mg-8Li-2Al-1Zn alloy was investigated by using hot compressive tests on a Gleeble-1500 D thermal simulation test machine at 523-723 K and at strain rates of 0. 01-10 s-1,and the flow stress constitutive equation and hot working map of the alloy were obtained. The stress-strain curves of the alloy show the characteristics of dynamic recrystallization. The flow stress of Mg-8Li-2Al-1Zn alloy decreases with increasing of deformation temperature and decreasing of strain rate. Dynamic recovery and dynamic recrystallization are verified by the microstructure evolution. The constitutive relation of Mg-8Li-2Al-1Zn alloy can be well described by hyperbolic-sine-type equation and Z parameter. The average values of the exponent n and the activation energy are 4. 62 and 139. 35 J /mol,respectively. According to the established processing map,it is shown that the optimum hot working parameters for the alloy are under 523-573 K and at 0. 1-1 s-1.