The microstructure and quasi-static compression properties at elevated temperatures of the aged vacuum die-casting Mg-4Al-4(La, Ce) alloy
Xiaoyu Liu, Taihe Le, Shuai Yuan, Jinhui Wang, Weili Cheng, Xiaoqiang Li, Peipeng Jin
Abstract
In this study, the hot compression test of the aged vacuum die-casting Mg-4Al-4(La, Ce) alloy was performed on Gleeble-3500 simulator. The mechanical properties of Mg-4Al-4(La, Ce) alloy were studied at different compression temperatures (100 °C, 150 °C, 200 °C, and 250 °C). During the compression, the microstructure evolution, texture, and dislocation slip of the Mg-4Al-4(La, Ce) alloy were systematically investigated by the electron backscatter diffraction (EBSD) technology. The results demonstrated that the flow stress decreased and the plasticity boosted with the increase in temperature. Mg-4Al-4(La, Ce) alloy exhibits excellent strength and toughness with elevated temperature. At 200 °C, it still has compressive strength of 204.5 MPa and compressive elongation of 59%. By observation of the microstructure, it has typical <0001>//CD texture after compression. It was found by in-grain misorientation axis (IGMA) analysis that the pyramidal <c+a> slip is sufficiently activated, which effectively improves the toughness of the alloy. In addition, the <c+a> dislocations and <a> dislocations are observed at 200 °C. Therefore, the excellent mechanical properties of Mg-4Al-4(La, Ce) alloy at high temperature are the result of grain refinement strengthening, second-phase reinforcement and work hardening.