过偏晶合金快速凝固过程中第二相液滴在液—液相变区内的粗化

建立了一个描述快速冷却条件下偏晶合金在液-液相变区内的第二相液滴粗化的数学模型，该模型考虑了第二相液滴的形核、扩散长大以及Brownian碰霎时超大型者的共同作用，模拟结果表明，第二相液滴间的Brownian碰撞是影响液滴粗化的一个重要的因素，快的冷却速率导致基体液相中液质过饱和度和第二相形核速率都升高到一个高的水平，同时得到较小的液滴平均半径和较大的液滴数目密度，这个模型对Al-30%In合金的预测结果与实验结果吻合较好，这说明本文所建立的模型在快速冷却条件下具有实际预测功能，这个模型同样可用于其它难混溶合金系。

COARSENING PROCESS OF MINORITY PHASE DROPLETS DURING RAPIDLY COOLING AN IMMISCIBLE ALLOY THROUGH THE MISCIBILITY GAP

A numerical model has been developed to describe the coarsening process of the minority phase droplets under common action of nucleation, diffusional growth as well as Brownian collision between droplets during rapidly cooling a hypermonotectic alloy through the miscibility gap. The simulated results show that Brownian collision is an important role of influencing the coarsening process. A faster cooling rate leads the supersaturation of solute in the matrix liquid and the nucleation rate of the minority phase to a higher level, but leads to a smaller droplet radius and a higher number density. This model has been used to predict satisfactorily the microstructural evolution of Al-30%In ribbon prepared with melt spinning method. The model has some predictive capabilities to rapid cooling processes and also yields some general relations applicable to other immiscible alloys.