(清華大學(xué) 機械工程系 先進(jìn)成形制造教育部重點實驗室，北京 100084)
摘 要: 通過耦合溶質(zhì)擴散方程，并考慮成分過冷和曲率過冷對界面平衡溶質(zhì)成分的影響，建立改進(jìn)的元胞自動機模型來模擬溶質(zhì)擴散控制的立方晶系合金的枝晶生長過程。模型在計算固液界面生長速率時考慮立方晶系枝晶擇優(yōu)生長取向 的影響，同時采用斜中心差分格式對界面生長速率方程進(jìn)行離散，從而能夠模擬擇優(yōu)生長取向與坐標(biāo)軸成不同夾角的枝晶生長形貌演變。為驗證模型的可靠性，模擬NH4Cl-H2O系透明合金單個等軸枝晶以及不同擇優(yōu)生長取向角的多個等軸枝晶和柱狀枝晶的形貌演化，模擬結(jié)果與實驗結(jié)果吻合較好。
關(guān)鍵字: 改進(jìn)的元胞自動機；擇優(yōu)生長取向；枝晶生長；數(shù)值模擬
（Key Laboratory for Advanced Materials Processing Technology, Ministry of Education,
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China）
Abstract:By coupling solute diffusion equation, and considering the effects of constitutional and curvature undercooling on interface equilibrium composition, a modified cellular automaton model (MCA) was proposed to simulate dendrite growth controlled by solute diffusion for cubic metals. The model considers the influence of preferred growth orientation on the normal velocity of solid and liquid interface for cubic metals. Meanwhile, a skew central difference scheme was used to discrete the normal velocity of solid and liquid interface. Therefore, the MCA model could simulate the dendrite morphology with preferred growth orientation misaligned with the x-axis. In order to validate the MCA model, single equiaxed dendrite, multiple equiaxed dendrites and columnar dendrites of NH4Cl-H2O transparent alloy with different preferred growth orientation angles ranging from 0° to 90° with respect to the horizontal direction were simulated, which has good agreement with the experimental data.
Key words: modified cellular automaton; preferred growth direction; dendritic growth; numerical simulation
