中文摘要：

建立凝固过程中宏观流动、传热、溶质传输与微观形核、生长过程双向耦合数学模型,并针对Al-Si二元合金凝固过程进行二维元胞自动机控制容积积分法（CA FV）耦合模拟。模型反映了流场下晶体逆流生长特性,考虑了温降导致的形核和生长以及形核和生长引起的固相分率变化对宏观场的影响,能预测凝固过程中再辉和晶间偏析等现象,反映合金液流动对合金的溶质分布以及凝固组织形貌的作用规律。与仅宏观传输模拟结果和无流动影响的模拟结果进行了对比,验证了耦合模型的优越性。同时考察了铸型尺寸对凝固组织形貌的影响。

英文摘要：

A coupled cellular automaton-finite volume（CA-FV） model for macroscopic fluid flow,heat transfer,solute transport and microscopic nucleation and grain growth procedure was developed and applied in an Al-Si binary alloy solidification process.The model reflects the dendrite growth kinetics in the presence of fluid flow,the nucleation and growth in CA scale due to the increase of undercooling,and the feedback of solid fraction and temperature to FV nodes due to the nucleation and growth.The coupled CA-FV model can predict the recalescence and the intergranular segregation during alloy solidification process,which shows great advantages compared with the results by FV model and CA-FV model without fluid flow.The effects of fluid flow on the solute distribution and the solidification morphologies,as well as the influence of ingot size on the solidification structures,were discussed with the CA-FV model.