Effect of Calcium on Fluidity of AZ91D Magnesium Alloy

The effects of Ca on the fluidity of AZ91D alloy were studied by spiral mould test.The identification of compositions and the observation of microstructure of the alloys were proceeded by XRD,EPMA,SEM and so on.The results indicate that the fluidity declined with 0.5% Ca addition due to the segregation of Ca at the grain boundaries.But when the quantity of Ca addition increased successively,the fluidity was improved because Al2Ca formed at the grain boundaries to prevent the growth of the grains.When the quantity of Ca addition exceeded 1.5%,the fluidity declined again.It could be explained by the formation of reticular Al2Ca phase.