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研究了Sr+RE复合变质对Al-40wt%Si合金的组织和性能的影响。结果表明,Sr+RE复合变质处理不仅对初晶硅和共晶硅具有变质作用,对枝晶α也有明显的细化作用。当RE加入量保持不变,随着Sr加入量的增加,初晶硅由角块状或大板片状先变为小块状再变为多角的大块状,边、角钝化;共晶硅由针片状变为纤维状加短杆状,最后为密实短杆状,甚至粒状;枝晶α由高度发达的树枝状转变为等轴晶,分布均匀。另外,随Sr加入量的增加,合金力学性能得到显著提高,抗拉强度提高37%,伸长率增加1倍多,硬度提高21%;当Sr加入量为0.05wt%～0.077wt%时,组织形貌最理想,综合力学性能最优。
The effect of Sr + RE composite modification on microstructure and properties of Al-40wt% Si alloy was investigated. The results show that Sr + RE compound metamorphism treatment not only has metamorphism on primary and eutectic silicon but also remarkably dendrite α. When the amount of RE remains unchanged, with the addition of Sr increases, the primary silicon by the block or platelet first into small pieces and then into a multi-angle block, side, corner passivation; a total of Crystalline silicon from the needle into a fibrous short bar-like, and finally dense short rod-shaped, or granular; dendrite α from the highly developed dendritic into equiaxed grains, evenly distributed. In addition, with the addition of Sr, the mechanical properties of the alloy were significantly improved, the tensile strength increased by 37%, the elongation increased by more than 1 times, the hardness increased by 21%; when the addition of Sr was 0.05wt% ~ 0.077wt% The best shape of the organization, the best overall mechanical properties.