Influence of pre- and post-extrusion heat treatments on microstructure and anisotropy of mechanical properties in a Mg–Al–Zn alloy

The pre-extrusion homogenization treatment at 400 °C effectively dissolves the eutectic phase and the liberated Al contributes in solid solution strengthening. After extrusion with prior homogenization, an abnormal grain growth occurs at the region favored by the local degree of dynamic recrystallization (DRX) and texture. This weakens the bulk texture, reduces the directional anisotropy in yield Stress and eliminates the strength differential effect without any loss of yield stress. The secondary recrystallization during post-extrusion annealing at 400 °C leads to pronounced grain growth, the texture is profoundly weakened and the yield stress becomes isotropic but is reduced by 33%.