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采用欧拉-欧拉法建立了稳恒磁场条件下描述过偏晶Al-Pb合金难混溶区凝固过程的数学模型,对过偏晶合金在有无磁场条件下的宏观偏析运动进行了数值模拟,研究了两相温度场、速度场、体积分数等物性参数对合金凝固显微组织演化的影响。结果表明,随着冷却过程的进行,有磁场作用下的温度场仍保持环形中心对称分布,有效的抑制了由于重力条件下较强的对流作用使中心高温区上移;速度场在磁场条件下为中心对称分布,因部分重力被抵消,Marangoni力的作用逐渐显现,速度明显降低且方向斜向下指向对称轴,凝固组织宏观偏析得到了有效的改善;磁场条件限制了L2项液滴的扩散长大和Ostwald熟化,同时有效限制了L2项液滴体积分数的增加,从而更有利于L2项液滴的均匀分布。
The Euler-Euler method was used to establish the mathematical model describing the solidification process of an immiscible Al-Pb alloy under the condition of a constant magnetic field. The macroscopic segregation movement of the transgranular alloy in the presence or absence of a magnetic field was numerically The effects of temperature, velocity field, volume fraction and other physical parameters on the microstructure evolution of the alloy were studied. The results show that with the progress of the cooling process, the temperature field under the action of magnetic field still maintains the symmetrical distribution of the annular center, which effectively suppresses the central high temperature region from moving upward due to the strong convection under the gravity condition. The velocity field under the magnetic field conditions As the center of the symmetry distribution, due to the partial gravity is offset, the role of Marangoni force gradually appear, the speed was significantly reduced and the direction of diagonal down to the symmetry axis, solidified macrosegregation has been effectively improved; magnetic field conditions limit the L2 items of the diffusion Grow and Ostwald ripening, while effectively limiting the increase of L2 volume fraction, which is more conducive to the uniform distribution of L2 droplets.