Phase field modeling of dendritic growth with high anisotropy

A phase field model of solidification with a reduced interface diffuseness was extended to crystal growth with sharp corners by using a regularization technique of gradient energy coefficient. The model was applied to simulate the highly anisotropic dendritic solidification in an undercooled pure material (symmetric model) and in a supersaturated alloy (one-sided model). Simulation was performed under a wide range of anisotropy covering the critical anisotropy, where corners appear in the equilibrium crystal shape. The growth rate of dendrite increased monotonically with increase in the anisotropy when the anisotropy strength was lower than the critical value. As the anisotropy crossed the critical value, however, the growth rate dropped down by about 10%, and then increased again with higher anisotropy. The growth velocity reached a maximum value, followed by a slight decrease with further increase in the anisotropy. Overall behavior of the dendritic growth with corners seemed to be understood by considering the decreasing range of the allowed interface orientation with increase in the anisotropy beyond the critical value.