Deformation behavior and constitutive model for dual-phase Mg-Li alloy at elevated temperatures  

双相Mg-Li合金的热变形行为和本构模型（英文）

作　　者：魏国兵[1] 彭晓东[1] 胡发平[1] Amir HADADZADEH 杨艳[1] 谢卫东[1] Mary A.WELLS 

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]Mechanical and Mechatronics Engineering Department,University of Waterloo

出　　处：《Transactions of Nonferrous Metals Society of China》2016年第2期508-518,共11页中国有色金属学报（英文版）

基　　金：Projects(CDJZR14130007;106112015CDJXY130011)supported by Fundamental Research Funds for the Central Universities,China

摘　　要：In order to study the deformation behavior and evaluate the workability of the dual-phase Mg-9Li-3Al-2Sr alloy, isothermal hot compression tests were conducted using the Gleeble-3500 thermal-mechanical simulator, in ranges of elevated temperatures （423-573 K） and strain rates （0.001-1 s^-1）. Plastic instability is evident during the deformation which is in the form of serrated flow; serrated yielding is attributed to the locking of mobile dislocations by the Mg and Li atoms which diffuse during the deformation. The relationships between flow stress, strain rate and deformation temperature were analyzed and the deformation activation energy and some basic material factors at different strains were calculated using the Arrhenius equation. The effects of temperature and strain rate on deformation behavior were represented using the Zener–Hollomon parameter in an exponent-type equation. To verify the validity of the constitutive model, the predicted values and experimental flow curves under different deformation conditions were compared, the correlation coefficient （0.9970） and average absolute relative error （AARE=4.41%） were calculated. The results indicate that the constitutive model can be used to accurately predict the flow behavior of dual-phase Mg-9Li-3Al-2Sr alloy during high temperature deformation.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。

关 键 词：constitutive model Mg-Li alloy plastic instability Zener-Hollomon parameter 

分 类 号：TG146.22[一般工业技术—材料科学与工程]