Role of twinning and slip in cyclic deformation of extruded Mg–3%Al–1%Zn alloys

The low-cycle tension–tension fatigue properties of extruded Mg–3%Al–1%Zn alloy plate have significantly different features in twinning-dominated samples and dislocation-dominated samples. The twinning-dominated samples show more pronounced cyclic hardening and longer fatigue life than those of the slip-dominated samples. The elongated lifetime of the twinning-dominated samples may be due to the roughness-induced crack closure.