枝晶生长的数值模拟

对朱、洪已发展的一种微观尺度cellular automaton(CA)模型做了进一步改进．在改进的模型中用二元合金的Gibbs-Thomson方程建立固／液界面的平衡关系．考虑了动力学和表面能各向异性对枝晶择优生长方向的影响．应用改进的模型模拟了不同择优取向的单枝晶在过冷熔体中的自由生长、定向凝固过程中柱状晶的竞争生长以及等轴晶的演变过程．模拟结果表明，改进后的模型成功地模拟出各种不同择优取向的单枝晶和多枝晶的生长形貌。

Numerical Modeling of Dendritic Growth

Based on the previous work reported by Zhu and Hong, a micro-scale cellular automaton (CA) model for modeling dendritic growth was further improved. In the present model, the solid/liquid interface equilibrium was determined using the Gibbs-Thomson equation for a simple binary alloy. It accounted for the effect of anisotropy in both interfacial kinetics and surface energy on the preferred growth orientation of a dendrite. The improved model was applied to simulate the dendritic features, in the cases of the free dendritic growth from an undercooled melt, competitive columnar growth in the directional solidification and equiaxed dendritic evolution. The simulation results show that the model can successfully predict the morphologies of both single and multi-dendrites with various preferred growth orientations.