采用P和RE对过共晶Al-Si合金进行复合变质处理,在不同P和RE添加量下对合金显微组织和力学性能进行了分析和测量。结果表明,P和RE复合变质对初晶硅和共晶硅均有很好的变质效果,初晶硅尺寸明显减小且棱角钝化,共晶硅由原来的长针状变为颗粒状。加入(质量分数,下同)0.08%P和0.6%RE时,合金的微观组织和力学性能同时达到最佳,室温和高温抗拉强度分别达到306MPa和187MPa,与未变质合金相比,提高了20%和34%;室温和高温伸长率分别达到0.48%和1.58%,与未变质合金相比,提高了40%和88%。 The hypereutectic Al-Si alloy was modified by P and RE. The microstructure and mechanical properties of the alloy were analyzed and measured under different P and RE loadings. The results show that the composite metamorphism of P and RE has good metamorphic effect on both the primary and the eutectic silicon. The size of the primary silicon decreases obviously and the corners are passivated. The eutectic silicon changes from the long needle to the granular form. When adding 0.08% P and 0.6% RE (mass fraction, the same below), the microstructure and mechanical properties of the alloy reached the optimum at the same time, and the tensile strength at room temperature and high temperature reached 306MPa and 187MPa, respectively. Compared with the unmodified alloy, 20% and 34% respectively. The elongation at room temperature and high temperature reach 0.48% and 1.58% respectively, which is 40% and 88% higher than that of unmodified alloy.