Effects of pre-compression on formation of dynamic precipitates and creep anisotropy of hot-extruded AZ91—2Y magnesium alloy

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 〈a〈 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 〈a〉 slip. The pyramidal 〈c+a〉 slip and twinning improve the creep anisotropy resistance significantly.