Grain refinement of AZ91D magnesium alloy by SiC

AZ91D magnesium alloy has been grain-refined by SiC particles. The effects of grain-refining parameters on its grain size have been investigated. Simultaneously, the corresponding refining mechanism has also been discussed. The results indicate that the SiC particle is an effective grain refiner for AZ91D alloy and can decrease the grain size from 311 μm of the not refined alloy to 71 μm under an optimized refining technology. The added SiC particles cannot directly act as the nucleation sites of α-Mg crystals and the Al4C3 particles formed from the reaction between the SiC particles and the molten alloy are the actual nucleation sites.