Crack propagation behaviour in magnesium binary alloys

The effect of alloying elements on crack propagation behaviour was investigated using extruded Mg-Ca and Mg-Zn binary alloys, with and without {} type deformation twins (DT). These alloys had similar microstructures grain boundary (GB) structure, basal texture, and grain size of ∼30 m. Most of the cracks in the Mg-Ca alloys were propagated along the high-angle GBs, i.e. exhibiting intergranular fracture, regardless of the existence of DT. On the other hand, crack propagation behaviour in the Mg-Zn alloy was influenced by the presence of twin boundaries (TBs). The fraction of TBs that was associated with the crack propagation showed higher in the twin-induced Mg-Zn alloy. These crack propagation tendencies resulted from modification of the TB energies by additional alloying elements.