采用元胞自动机法模拟二元规则共晶生长

基于元胞自动机方法,建立了二元规则共晶生长的数值模拟模型.该模型耦合宏观温度场,考虑了溶质扩散、成分过冷以及曲率过冷等重要因素,实现了二元规则共晶的稳态层片生长.以共晶模型合金为对象,研究了定向凝固条件下不同过冷度、初始层片间距、温度梯度及凝固速率对共晶两相生长形貌及层片间距的影响,再现了两相在溶质扩散及界面能的相互作用下通过形核、分岔、湮没及合并等机理实现共晶层片间距的调整.模拟得到的结果与Jackson-Hunt模型及前人实验结果规律一致.将模型扩展到三维系统,验证了二元规则共晶生长三维模拟的可行性. 关键词： 规则共晶 生长形貌 层片间距 CA方法

Modeling of regular eutectic growth of binary alloy based on cellular automaton method

Based on cellular automaton method, a numerical model was developed for the regular eutectic growth of binary alloy. By coupling with the macro-temperature field and considering the solute diffusion, the constitutional undercooling and the curvature undercooling, modeling of the steady-state lamellar eutectic growth was achieved. A systematic investigation on eutectic growth morphology and lamellar spacing of a model alloy was made under unidirectional solidification conditions with different undercoolings, initial lamellar spacings, temperature gradients and solidification rates. The results reproduced the adjustment of lamellar spacing of two eutectic phases under the interaction between solute diffusion and surface energy by mechanisms of nucleation, lamellar branching, lamellar termination and overgrowth. The simulated results were in agreement with those predicted by the Jackson-Hunt model and experimental results by other researchers. Finally, the model was extended to three dimensional systems, which verified its feasibility of modeling the three-dimensional eutectic growth.