Ni-Cu二元合金定向凝固的相场法数值模拟

Phase-Field Simulation of Binary Alloy during Directional Solidification

采用相场方法对二元合金的定向凝固进行二维数值模拟,以Ni-Cu合金为例,展示了界面形态的演化过程,研究了相场参数对界面形态的影响。结果表明,随着界面厚度的减小,晶体生长形态由胞晶转变为树枝晶,尖端速度增大,但其稳定性下降;各向异性系数越小,尖端生长速度越小,越易于侧向分支的生长,形成胞状枝晶:热扰动幅值a对界面形态也有重要影响,当a取值适当时,便引发侧向分支,形成胞状枝晶,同时尖端速度也受到影响。

A phase-field method for two-dimensional numerical simulation of binary alloy during directional solidification is studied, the evolution of the interface morphology is showed and the effects of phase-field parameters on interface morphology are formulated for Ni-Cu binary alloy. The results indicate that, with the decrement of interface width, the transition of cells to dendrites occur, the tip velocity was increasing and the stability of the tip was descending. The smaller the anisotropy is, the smaller the tip velocity is, and the easier the side-branches grow and form cellular dendrites. The amplitude of fluctuation a has an important effect on the interface morphology. When an appropriate value is assigned to a, the noise can enhance the emergence of side-branches, and form cellular dendrites, and influence the tip velocity at the same time.