溶质梯度影响非等温凝固过程的相场法模拟

Phase-field Simulation of Influence of Solute Gradient to Process of Non-Isothermal Solidification

采用相场法模拟了Ni-Cu二元合金非等温凝固过程溶质梯度对枝晶生长的影响。结果表明:非等温凝固时,潜热的释放使固相区的温度比液相中的高,在二次枝晶生长较为密集的中心区域温度最高,固相区温度升高会使得金属重熔,发生重熔现象,晶体的生长速度和凝固区域的温度随之出现波动。溶质梯度对溶质分布影响较大,溶质梯度增加,固相率提高,溶质分配系数k增大,固相区溶质富集,形成了过饱和的固相,溶质截流效应明显。

Dendritic growth in a nickel/copper system under non-isothermal condition and the influence of solute gradient on this process were studied. The results indicate that the release of latent heat will result in higher temperature in solid area than liquid area, the highest temperature appears in the center area of some dengdritic growth tips crowd, and increased temperature in solid area will make the alloy remelt, recalescence phenomenon occurs, the velocity of dendritic growth and temperature of solidification area will accordingly fluctuated. Adding solute gradient will increase the percentage of solid phase and coefficient of solute distribute, make solute enriched in solid area and over saturated solid phase formed, which means clearly that solute trapping phenomenon occurred in the process of solidification.