(1. 中國科學(xué)院 金屬研究所，沈陽 110016；
2. 中國科學(xué)院大學(xué)，北京 100049)
摘 要: 針對固溶態(tài)Mg-11Gd-4Y-2Zn-0.4Zr合金，利用金相顯微鏡(OM)、掃描電子顯微鏡(SEM)和電子背散射衍射(EBSD)技術(shù)結(jié)合剪應(yīng)力等效施密特因子計算，系統(tǒng)研究該合金在350~450 ℃熱扭轉(zhuǎn)過程中組織演化規(guī)律及變形機理，為該合金剪切變形工藝的開發(fā)提供理論支撐。結(jié)果表明：扭轉(zhuǎn)變形后，該合金原始等軸晶粒沿著剪切方向被拉長，同時，形成具有剪切特征的變形織構(gòu)。350 ℃變形時，該合金變形機制以基面 滑移為主，部分晶粒發(fā)生拉伸孿晶，孿晶變體的選擇滿足施密特定律，且當(dāng)基面 滑移和拉伸孿晶受抑制時，發(fā)生LPSO相扭折變形協(xié)調(diào)應(yīng)變；400 ℃變形時，部分晶粒出現(xiàn)二次孿晶，并在孿晶界和扭折界面發(fā)生動態(tài)再結(jié)晶；450 ℃變形時，形成變形晶粒和再結(jié)晶晶粒的“雙模”組織，再結(jié)晶織構(gòu)為隨機織構(gòu)，可以顯著弱化變形織構(gòu)。
關(guān)鍵字: Mg-Gd-Y-Zn-Zr合金；熱扭轉(zhuǎn)；孿晶；長周有序結(jié)構(gòu)相；動態(tài)再結(jié)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)
