过共晶Al-Si合金快速凝固组织演变

以群体动力学模型为基础,在充分考虑合金的热物性参数、过饱和度以及第二相形核率变化的基础上,提出描述该合金快速凝固组织演变的数学模型,并结合A390合金进行计算。结果表明:随着雾化合金液滴尺寸的减小,平均冷却速度增加,而初生Si相长大时间减少,所析出初生Si相的尺寸及体积分数也不断减小;当粉末尺寸减小到某一临界值时,初生Si相消失,从而使不同尺寸粉末的微观组织发生很大的变化。计算结果与实验结果吻合较好,说明此提出的模型可以较好地预测过共晶Al-Si合金快速凝固组织的形成,从而为进一步研究高硅合金材料的组织演变奠定基础。

Microstructure evolution of hypereutectic Al-Si alloy during rapid solidification

Based on both the population dynamics model and the continuous variety of thermo-physical parameters, supersaturation and nucleation rate, a model was developed to describe the microstructure evolution of hypereutectic Al-Si alloy during rapid solidification, and was solved for A390 alloy. The results show that, with the droplet size decreasing, the average quenching velocity increases and the growth time, size and volume fraction of primary Si decrease. The primary Si of powder particle is extinct under a critical size, which result in the different microstructures of various powder particles. The results of atomization experiments of hypereutectic Al-Si alloys show a good agreement with the theoretical calculations. The model can be used to predict satisfactorily the microstructures evolution of hypereutectic Al-Si alloys.