(清华大学 机械工程系 先进成形制造教育部重点实验室，北京 100084)
摘 要: 基于枝晶生长的基本传输过程和元胞自动机(Cellular Automaton，简称CA)模型基本原理，建立符合镁合金密排六方结构特点的凝固过程形核、晶体生长的数学模型。模型耦合宏观温度场和微观组织模拟计算，考虑溶质扩散、曲率过冷和各向异性等重要因素的影响，定义界面单元捕获规则，能够模拟枝晶生长的形态。应用本模型对单个等轴晶生长、等轴晶多晶粒生长及定向凝固中的柱状晶生长进行模拟并与实验结果进行对比，模拟结果与实验结果吻合较好，验证了模型的正确性。
关键字: 镁合金；密排六方结构；微观组织模拟；元胞自动机方法；枝晶形貌
（Department of Mechanical Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, China）
Abstract:A new model for the nucleation and dendritic growth of magnesium alloys during solidification process was developed, which was based on cellular automaton(CA) method and the classical transfer equations during dendritic growth and is suitable for the hexagonal close-packed crystal structure. The model coupled the temperature field calculation and microstructure simulation. The solute diffusion, curvature undercooling and anisotropy were also considered in the model, all of which have significant influence on the dendrite evolution. By setting up the CA-cell capturing rules, the dendritic growth morphology can be modeled. Applications of the model in single equiaxed dendritic growth, multiple equiaxed dendritic growth and columnar grain growth in directional solidification were presented. The microstructure simulation results were compared with the experimental results and they were in good agreement in dendritic morphology, which validates the proposed model in the prediction of dendritic growth of magnesium alloys.
Key words: magnesium alloy; hexagonal close-packed structure; microstructure simulation; cellular automaton method; dendritic morphology
