Phase Field Model for Solidification of Fe-Cr-C Ternary Alloys Based on KKS Model

The phase field method is an important method to study structural phase transition, dendrite growth, and material microstructure and phase transition behavior. The KKS model was used to study the microstructure formation mechanism and phase field equation establishment process of the KKS model in the solidification process of the ternary Fe-Cr-C alloy. Additionally, a new ternary phase field equation has been proposed and established, taking into account the solute free energy distribution of new elements. The micro-segregation of the Fe-Cr-C alloy has also been studied via a thin interface model of phase field theory, and the proposed model was applied. The increase of the Cr element caused the dispersion of ternary dendrite growth morphology and the slowing down of tip velocity. The simulation was verified by high-temperature confocal experiments. Under the influence of chromium diffusion, the dendritic arms were filled with Cr-C alloy. The undercooling conditions of the dendrites were set to 28 K, 29 K, 30 K, and 31 K in sequence, and the comparison of dendrite growth showed that, as the initial cooling temperature increased, the growth rate of the secondary dendrite arms increased, and the spacing between the secondary dendrite arms decreased.