PHASE FIELD SIMULATION ON DENDRITIC GROWTH IN PRESSURIZED SOLIDIFICATION OF Mg-Al ALLOY

摘要

A phase field model coupled with thermodynamic calculation for describing the dendritic growth in pressurized solidification of Mg-Al alloy during squeeze casting has been developed, in which the effects of pressure on the Gibbs free energy and chemical potential of solid and liquid phases, the solute diffusion coefficient, and the solute partition coefficient were considered. With the comparison of the dendritic growth under atmospheric and elevated pressures, the manifestations of the effect of pressure on the microstructure evolution were discussed. The results indicated that the dendritic growth rate tends to increase and the secondary dendrite arms are more developed as the pressure is increased from 0.1 to 100MPa, which showed a good agreement with the experimental results of direct squeeze casting of Mg-Al alloy.