(西北工業(yè)大學(xué) 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室， 西安 710072)
摘 要: 從熱力學(xué)角度分析了三元合金凝固過程中的溶質(zhì)分凝行為， 利用耦合熱力學(xué)計(jì)算技術(shù)研究了Al-Si-Mg三元合金溶質(zhì)分凝因數(shù)在凝固過程中的變化規(guī)律， 獲得了其與固相體積分?jǐn)?shù)的定量關(guān)系， 進(jìn)而預(yù)測了不同條件下Al-Si-Mg三元合金的凝固過程和相析出規(guī)律。 實(shí)驗(yàn)發(fā)現(xiàn)三元合金中溶質(zhì)分凝因數(shù)在凝固過程變化巨大， 采用二元系中的參數(shù)使得對共晶種類和共晶分?jǐn)?shù)的預(yù)測均與實(shí)驗(yàn)值有較大偏差。 采用耦合熱力學(xué)計(jì)算技術(shù)， 獲得了分凝因數(shù)在凝固過程中的變化規(guī)律， 使預(yù)測值更好地吻合于實(shí)驗(yàn)結(jié)果。
關(guān)鍵字: 溶質(zhì)分凝；三元合金； 熱力學(xué)計(jì)算； 共晶分?jǐn)?shù)
（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
