Simulation of facet dendrite growth with strong interfacial energy anisotropy by phase field method
来源期刊：中南大学学报(英文版)2015年第3期
论文作者：YUAN Xun-feng(袁训锋) LIU Bao-ying(刘宝盈) LI Chun(李春) ZHOU Chun-sheng(周春生) DING Yu-tian(丁雨田)
文章页码：855 - 861
Key words：phase field; facet dendrite; hcp materials; interfacial energy anisotropy; dimensionless undercooling
Abstract: Numerical simulations based on a new regularized phase-field model were presented, to simulate the solidification of hexagonal close-packed materials with strong interfacial energy anisotropies. Results show that the crystal grows into facet dendrites, displaying six-fold symmetry. The size of initial crystals has an effect on the branching-off of the principal branch tip along the <100> direction, which is eliminated by setting the b/a (a and b are the semi-major and semi-minor sizes in the initial elliptical crystals, respectively) value to be less than or equal to 1. With an increase in the undercooling value, the equilibrium morphology of the crystal changes from a star-like shape to facet dendrites without side branches. The steady-state tip velocity increases exponentially when the dimensionless undercooling is below the critical value. With a further increase in the undercooling value, the equilibrium morphology of the crystal grows into a developed side-branch structure, and the steady-state tip velocity of the facet dendrites increases linearly. The facet dendrite growth has controlled diffusion and kinetics.
YUAN Xun-feng(袁训锋)1, 2, LIU Bao-ying(刘宝盈)1, LI Chun(李春)2, ZHOU Chun-sheng(周春生)2, DING Yu-tian(丁雨田)3
(1. School of Electronic Information and Electrical Engineering, Shangluo University, Shangluo 726000, China;
2. Shaanxi Key Laboratory of Comprehensive Utilization of Tailing Resources
(Shangluo University), Shangluo 726000, China;
3. State Key Laboratory of Gansu Advanced Non-Ferrous Metal Materials
(Lanzhou University of Technology), Lanzhou 730050, China)
Abstract:Numerical simulations based on a new regularized phase-field model were presented, to simulate the solidification of hexagonal close-packed materials with strong interfacial energy anisotropies. Results show that the crystal grows into facet dendrites, displaying six-fold symmetry. The size of initial crystals has an effect on the branching-off of the principal branch tip along the <100> direction, which is eliminated by setting the b/a (a and b are the semi-major and semi-minor sizes in the initial elliptical crystals, respectively) value to be less than or equal to 1. With an increase in the undercooling value, the equilibrium morphology of the crystal changes from a star-like shape to facet dendrites without side branches. The steady-state tip velocity increases exponentially when the dimensionless undercooling is below the critical value. With a further increase in the undercooling value, the equilibrium morphology of the crystal grows into a developed side-branch structure, and the steady-state tip velocity of the facet dendrites increases linearly. The facet dendrite growth has controlled diffusion and kinetics.
Key words:phase field; facet dendrite; hcp materials; interfacial energy anisotropy; dimensionless undercooling
