Numerical modelling of microstructure evolution and dendrite growth in alloy solidification process

A modified cellular automaton method was presented to simulate the evolution of dendrite microstructure accounting for the heterogeneous nucleation, the preferential growth orientation, the solute redistribution both in liquid and solid, the interface curvature and the growth anisotropy during solidification. The effect of the constitutional undercooling and curvature undercooling was incorporated based on the solid/liquid interface equilibrium. The finite difference method coupled with CA model was used to calculate the temperature and solute fields. The free growth of equiaxed grain and competitive growth of columnar grain in the directional solidification was predicted. The effect of the bubble on the dendrite growth and the solute distribution was investigated. The simulated results were compared with those obtained experimentally.