(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410083)
摘 要: 研究了高温条件下Mg-Gd-Y-Zr 合金形变孪生变体的选择规律。在350 ℃及真应变为0.05时通过单向压缩铸态Mg-Gd-Y-Zr合金试样，获得形变孪生组织。利用背散射电子衍射(EBSD)技术与透射电子显微镜(TEM)确定孪生类型为{ } 孪生。通过对比EBSD测试结果与理论计算结果，确定了孪生变体。采用Schmid因子准则与Taylor准则分析了{ } 孪生发生的规律。结果表明：Schmid因子准则仅仅考虑孪生变体的Schmid因子，其预测结果与实验结果不符；而Taylor准则考虑了孪生、基面滑移与非基面滑移的相互协调作用，可准确预测{ }孪生的变体选择结果；稀土镁合金的高温形变也需要孪生参与协调塑性变形。
关键字: 镁合金；形变孪生；Schmid 因子；Taylor准则
elevated temperature in Mg-RE alloy
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The selection law of deformation twinning variants at elevated temperature in Mg-Gd-Y-Zr alloy was investigated. The microstructures containing deformation twins were prepared by compressing as-cast Mg-Gd-Y-Zr alloy at 350 ℃ and low true strain of 0.05. The observed { } twins were characterized by electron backscatter diffractometry (EBSD) and transmission electron microscopy (TEM). Comparison between EBSD analysis and theoretical calculation was conducted to identify the twinning variants. Two methods, Schmid factor and Taylor criterion, were used to analyze the law for occurrence of twinning variants. The results reveal that Schmid factor fails to predict the activated twinning variants, while Taylor criterion allows the experimental observations to be readily predicted considering { } twins, basal slip and non-basal slips. For Mg-Re alloy, deformation twinning at elevated temperature is still necessary to accommodate the plastic strain along with dislocation slip.
Key words: magnesium alloy; deformation twins; Schmid factor; Taylor criterion
