Microstructure evolution of Mg–Zn binary alloy during a direct extrusion process

The microstructure evolution of Mg–2.4 at.% Zn binary alloy was examined during extrusion at low temperature. Fine-grained structures were formed near the grain boundary due to dynamic recrystallization. Rod-shaped precipitates were also formed before the extrusion and were elongated and/or torn off by the strain; the precipitate morphology changed from rods to spheres. The spherical precipitates pin the dislocations; they are the nucleation site for new grains and promote recrystallization.