Abstract:Based on the Wheeler model and the Eggleston regularization technique of the anisotropy of strong interface energy, the phase-field model was built by coupling the solute field with temperature field, and the dendrite growth process of the anisotropy of strong interface energy of Ni-Cu alloy was simulated. The results show that the variation of interface orientation discontinuous and the corners form on the dendrite with the anisotropy of strong interface energy, the dendrites grow fast due to the large temperature gradient and solute gradient. With an increase in anisotropy strength, the growth velocity of dendrite increases when the anisotropy strength is lower than the critical value; when the anisotropy strength equals the critical value, the growth velocity drops down by about 4.34%; with an increase again in anisotropy strength (larger than the critical value), the growth velocity reaches the maximum value and then tends to decrease. The equilibrium morphology of the crystal grows into a square-like one in the situation of low dimensionless supercooling degree; with an increase in dimensionless thermal supercooling degree, the equilibrium morphology of the crystal changes from square-like to dendrite, the growth velocity of dendrite increases exponentially and then increases linearly, and the dendrite growth is under control from diffusion to kinetics.

Key words: Ni-Cu alloy; anisotropy strength; interface energy; supercooling degree; phase-field method; dendrite growth