(1. 中国科学院 金属研究所，沈阳 110016；
2. 中国科学院大学，北京 100049)
摘 要: 针对固溶态Mg-11Gd-4Y-2Zn-0.4Zr合金，利用金相显微镜(OM)、扫描电子显微镜(SEM)和电子背散射衍射(EBSD)技术结合剪应力等效施密特因子计算，系统研究该合金在350~450 ℃热扭转过程中组织演化规律及变形机理，为该合金剪切变形工艺的开发提供理论支撑。结果表明：扭转变形后，该合金原始等轴晶粒沿着剪切方向被拉长，同时，形成具有剪切特征的变形织构。350 ℃变形时，该合金变形机制以基面 滑移为主，部分晶粒发生拉伸孪晶，孪晶变体的选择满足施密特定律，且当基面 滑移和拉伸孪晶受抑制时，发生LPSO相扭折变形协调应变；400 ℃变形时，部分晶粒出现二次孪晶，并在孪晶界和扭折界面发生动态再结晶；450 ℃变形时，形成变形晶粒和再结晶晶粒的“双模”组织，再结晶织构为随机织构，可以显著弱化变形织构。
关键字: Mg-Gd-Y-Zn-Zr合金；热扭转；孪晶；长周有序结构相；动态再结晶
（1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China）
Abstract:The microstructure evolution and deformation mechanism of solution treated Mg-11Gd-4Y-2Zn-0.4Zr under hot torsion conditions were investigated by optical microscope (OM), scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The results show that the original equiaxed grains are elongated along the shear direction, and the deformation textures with shear-induced characteristics are formed as well. Under 350 ℃, the deformation mechanism of the alloy is dominated by basal slip. In addition, the extension twins appear inside some grains and the selection of twin variants obeys to the Schmid’s law. When basal slip and extension twins are restrained, the kinking of LPSO phase occurs to accommodate the plastic strain. When deformed at 400 ℃, secondary twinning is detected, and the dynamic recrystallization noteworthy occurs at twinning boundary and kink boundary. When the deformation temperature increases to 450 ℃, a bimodal microstructure consisting of deformed grains and recrystallized grains is produced. Moreover, the recrystallized grains with random texture can weaken the deformed texture effectively.
Key words: Mg-Gd-Y-Zn-Zr alloy; hot torsion; twining; long period stacking ordered phase (LPSO); dynamic recrystallization (DRX)
