Microstructure and properties of AZ91D alloy with Ca additions

Ca additions from 0.1 to 1.0 wt.% to AZ91D alloy produced some grain refinement and thinning of β-Mg17Al12 phase. Increasing the Ca content resulted in the formation of Al2Ca phase as well as in the reduction in quantity of β-Mg17Al12 phase. The hot tearing susceptibility of the alloy substantially increased with Ca content rise. The ultimate tensile strength and relative elongation worsened that was explained by the presence of Al2Ca phase on the grain boundaries. The improvement in the yield strength was connected with the grain refinement of the alloy induced by the restriction of the grain growth due to Ca aggregations on the boundaries.