Evolution of 3D microstructure and correlation with deformation behavior of as-cast Mg-4Zn-xCa alloys

In this study, X-ray microtomography results aided with fractography have been utilized to elucidate the effect of the distribution of the secondary phases on the damage mechanism of the Mg-4Zn-xCa (x = 0, 0.2, 0.4, 0.6, 1.0 wt%) alloys. The alloy Mg-4Zn exhibited a 2 -a phase microstructure comprising of alpha-Mg matrix and the second phase (MgZn), which converted to an interconnected network of Ca2Mg6Zn3 phase along grain boundaries with an increase in Ca content. The compressive strength increased with the increase in Ca content up to 0.4 wt% due to the formation of the Ca2Mg6Zn3 phase. However, it further decreased due to easier crack propagation through the 3D network of Ca2Mg6Zn3 at grain boundaries.