噪声影响凝固微观组织的相场法模拟

Phase-field Simulation of Solidification Microstructure by the Effect of Noise

采用kim模型,利用耦合溶质场的相场模型,对Al-Cu二元合金的定向凝固过程进行模拟,为了简化计算,采用了温度冻结近似。研究了扰动对固液界面的形态及微观组织演化的影响。结果表明,引入界面扰动,使得固液界面的稳定性受到破坏,界面形态由初始平面转变为胞晶,在胞状生长过程中竞争淘汰是主要的生长方式;随着扰动强度的增加,胞状晶粒细化,界面推进速度增加,界面前沿的溶质扩散层变薄,微观偏析程度减小,溶质截留现象严重。

The direction solidification process of binary Al-Cu alloy was simulatedutilizing Kim model and the coupled solute field phase model model. Frozen temperature approximation is adopted to simplify the modeling, the effect of noise on interface morphology and microstructure evolution was studied. The results indicate that, the stability of interface is destroyed by introducing interface fluctuation, the interface morphology transfers from plane to cellular and the competition selection is the dominated mode in the process of the celluar growth. With increase of noise amplitude, cellular grains become fine, the impelling rate of the interface increases, the the solute diffusion layer ahead of the interface becomes thinner, the degree of microsegregation reduces, the solute trapping is obvious.