Influence of rapid solidification on the microstructure of AZ91HP alloy

This paper presents differences of microstructure between conventionally casting and rapidly solidified AZ91HP alloy. The experimental results showed that rapid solidification changed the morphology of microstructure. The grain size was refined and homogeneously distributed β-Mg17Al12 phase was obtained. High cooling rate increased nucleation sites of α-Mg, refined microstructure and decreased the proportion of brittle β-Mg17Al12 in the eutectic (α-Mg and β-Mg17Al12). The decrease of microporosity should be attributed to the grain refinement and application of copper mould.