(西北工业大学 凝固技术国家重点实验室， 西安 710072)
摘 要: 从热力学角度分析了三元合金凝固过程中的溶质分凝行为， 利用耦合热力学计算技术研究了Al-Si-Mg三元合金溶质分凝因数在凝固过程中的变化规律， 获得了其与固相体积分数的定量关系， 进而预测了不同条件下Al-Si-Mg三元合金的凝固过程和相析出规律。 实验发现三元合金中溶质分凝因数在凝固过程变化巨大， 采用二元系中的参数使得对共晶种类和共晶分数的预测均与实验值有较大偏差。 采用耦合热力学计算技术， 获得了分凝因数在凝固过程中的变化规律， 使预测值更好地吻合于实验结果。
关键字: 溶质分凝；三元合金； 热力学计算； 共晶分数
（State Key Laboratory of Solidification Processing,
Northwestern Polytechnical University, Xi′an 710072, China）
Abstract:Variation of solute partition coefficient was studied in dendritic solidification process of Al-Si-Mg alloys. The calculations were coupled with CALPHAD technology. It is found that the partition coefficient changes greatly during solidification process, which is very important to the microsegregation and the precipitation of various phases. The solidification path and eutectic fractions were obtained by employing the binary partition coefficient and CALPHAD technology separately. The results show that great errors exist under assuming the partition coefficient as a const due to the interaction between solutes. Coupled CALPHAD technology with microscale solidification model used in this paper, the predicted solidification processes of Al-Si-Mg alloys agree well with the experimental results.
Key words: solute partition; multicomponent alloy; CALPHAD; eutectic fraction
