二元合金等温凝固过程的相场模型

基于Ginzberg-Landau理论，发展了一个与WBM模型和KKS模型一致的新相场模型.并利用该相场模型与溶质场耦合计算，以Al-65%Cu合金为例模拟了不同过冷度条件下，二元合金凝固过程的等轴枝晶生长过程.研究过冷度对二元合金等温凝固过程的等轴枝晶生长以及溶质场分布的影响.结果表明：随着过冷度的增大，枝晶的二次枝晶更加发达，浓度Peclet数和枝晶尖端的生长速率增大，而枝晶尖端的曲率半径减小，枝晶前沿的溶质富集现象也更严重；另外，计算结果与Ivantsov理论符合较好. 关键词： 相场法 枝晶生长 溶质场 Ivantsov理论

Phase-field modeling of isothermal solidification in binary alloy

A new phase-field model is developed based on the Ginzberg-Landau theory,which is consistent with WBM model and KKS model. The dendritic growth process during the solidification in a Al-6.5%Cu binary alloy was simulated using the phase-field model. Solute diffusion equation was solved simultaneously. The effects of undercooling on the dendritic growth and solute profile in isothermal solidification of binary alloy were investigated. The results indicate that the dendritic has well-developed secondary arms with the increase of undercooling. Correspondently,the solute Peclet number and the tip speed increases,the tip radius decreases,and the solute segregation in solid-liquid interface increases. The results agree well with Ivantsov theory.