Research on Phase-Field Model of Three-Dimensional Dendritic Growth for Binary Alloy

摘要

Based on the three-dimensional phase-field model (KKS model) of single-phase system and pure diffusion dendritic growth for binary alloy, the normal vector of dendritic solid-liquid interface migration direction is employed as an independent variable to describe phase-field governing function and interfacial free energy anisotropy equation, and the angle between the normal direction of dendritic growth interface migration and the optimal growth direction is used to describe interfacial free energy anisotropy function, and the purpose is to improve phase-field model. Taking Al-Cu binary alloy for example, the three-dimensional dendritic growth with different growth orientations and the dendritic tip growth velocities under different undercoolings are simulated. The simulation results are compared with the KKS model's simulation results and the predicted results of the classical solidification theory (LKT (BCT) theory). The results show that the simulation results agree well with the theoretical prediction results. The definitional domains of three angle variables in the interfacial free energy anisotropy function used this paper research are the same and there is a one-to-one relationship among them, and then the numerical simulation of solid-liquid interface evolution about different grains' common growth with different optimal growth orientations is realized.