非对角扩散项对三元合金枝晶生长影响的相场法研究

Phase-field Simulation on the Effect of Off-diagonal Diffusion Terms on the Dendritic Growth of Al-Cu-Mg Ternary Alloys

采用考虑非对角扩散项的多元合金枝晶生长相场模型,研究了Al-Cu-Mg三元合金等温凝固条件下的枝晶生长。结果表明,非对角扩散项的引入使得溶质传输条件发生改变,负的非对角项引入阻碍了溶质积累,使枝晶尖端生长速度降低、枝晶尖端液相浓度升高、液相侧浓度梯度变小、固相及枝晶间液相溶质的平均浓度均降低。

The isothermal dendritic growth of Al-Cu-Mg ternary alloy was simulated utilizing a multicomponent phase field model involved off-diagonal diffusion terms. The results indicate that the introduction of off-diagonal diffusion terms change the solute transport conditions, the negative off- diagonal diffusion terms block the solute accumulation, decrease the dendritic tip velocity, increase the dendritic tip composition and reduce the composition gradient in the liquid phase side and the average compositions of the solid phase and the inter-dendritic liquid phase.