以二元合金相场模型为基础,建立了耦合溶质场的相场模型,采用有限差分法对控制方程进行数值求解,模拟了Al-Cu二元合金在等温凝固时晶粒的生长过程。研究了过冷度和晶粒间距对晶粒生长行为的影响,分析了溶质扩散对晶粒生长长度和生长速率的影响。结果表明:在低的过冷度和小的晶粒间距下,晶粒趋于球形生长;而在高的过冷度或大的晶粒间距下,晶粒趋于树枝状生长。在高晶粒密度和缓慢冷却条件下,晶粒周围浓度场的相互叠加使得晶粒生长界面前沿的溶质分布更均匀,有利于晶粒呈球形生长,球晶可以在液相中直接形成。 Based on the binary alloy phase field model, a phase field model of coupled solute field was established and the governing equations were numerically solved by finite difference method. The growth process of the grains during the isothermal solidification of Al-Cu binary alloy was simulated. The effects of undercooling and intergranular spacing on grain growth behavior were investigated. The effect of solute diffusion on grain growth length and growth rate was also studied. The results show that the grains tend to grow spherically at low degrees of supercooling and small intergranular spacing, whereas the grains tend to dendritic at high supercooling or large intergranular spacing. Under the conditions of high grain density and slow cooling, the superposition of the concentration fields around the grain makes the solute distribution more uniform along the grain growth interface, which is favorable for the grain growth. The spherulites can be directly formed in the liquid phase.