Study on the near-liquidus casting of AZ91D magnesium alloy

The near-liquidus casting process was used in casting AZ91D alloy. and its microstructure was compared with that prepared by liquid casting. The effects, of cooling rate in casting process and the holding time in near-liquidus on microstructure tire were also observed. The results indicate that the microstructure obtained from liquid casting is similar to that of conventional casting. and dendriticization is promoted at higher cooling rate. On the contrary. near-liquidus casting is beneficial to refining and spheriodization of casting microstructure, however, whose effect is not apparent as comparing with alumimum alloy. The refining degree increases with increasing cooling rate, and the evolution mechanism of casting micrustructure for near-liquidus casting was discussed.