(清華大學(xué) 機(jī)械工程系 先進(jìn)成形制造教育部重點(diǎn)實(shí)驗(yàn)室，北京 100084)
摘 要: 基于枝晶生長的基本傳輸過程和元胞自動機(jī)(Cellular Automaton，簡稱CA)模型基本原理，建立符合鎂合金密排六方結(jié)構(gòu)特點(diǎn)的凝固過程形核、晶體生長的數(shù)學(xué)模型。模型耦合宏觀溫度場和微觀組織模擬計(jì)算，考慮溶質(zhì)擴(kuò)散、曲率過冷和各向異性等重要因素的影響，定義界面單元捕獲規(guī)則，能夠模擬枝晶生長的形態(tài)。應(yīng)用本模型對單個(gè)等軸晶生長、等軸晶多晶粒生長及定向凝固中的柱狀晶生長進(jìn)行模擬并與實(shí)驗(yàn)結(jié)果進(jìn)行對比，模擬結(jié)果與實(shí)驗(yàn)結(jié)果吻合較好，驗(yàn)證了模型的正確性。
關(guān)鍵字: 鎂合金；密排六方結(jié)構(gòu)；微觀組織模擬；元胞自動機(jī)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
