Effects of pre-compression on formation of dynamic precipitates and creep anisotropy of hot-extruded AZ91-2Y magnesium alloy
(1. Key Laboratory of Efficient & Clean Energy Utilization, School of Energy and Power Engineering, Changsha University of Science & Technology, Changsha 410114, China;
2. Japan Electric Power Central Research Institute, Tokyo 240-0196, Japan;
3. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China)
2. Japan Electric Power Central Research Institute, Tokyo 240-0196, Japan;
3. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China)
Abstract: The creep anisotropy behavior under different stresses at 180 °C of hot-extruded AZ91-2Y magnesium alloy with pre-compression (PC) and without pre-compression (NPC) was studied. Microstructure, texture and mechanical properties of the alloy were examined by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and tensile creep tests. The results revealed that the creep resistance was proportional to the volume fraction of spherical Mg17Al12 precipitates. The dynamic precipitation of large volume fraction of lamellar Mg17Al12 in NPC samples leads to the basal áa？ slip as the dominant creep mechanism, and the NPC samples have obvious anisotropy. In the PC samples, dynamic precipitation of large volume fraction of spherical Mg17Al12 has inhibitory effect on the basal áa？ slip. The pyramidal ác+a？ slip and twinning improve the creep anisotropy resistance significantly.
Key words: magnesium alloy; creep anisotropy; pre-compression; twin; dislocation