P、Sr、RE变质对过共晶Al-Si合金组织形态的影响

采用P、Sr、混合RE对含Si量22%～26%的过共晶铝硅合金进行变质处理,利用金相显微镜分析了单一元素变质及复合变质对合金初晶硅和共晶硅组织形态的影响。结果表明,P为初晶硅变质元素,Sr为共晶硅变质元素,RE能同时细化初晶硅和共晶硅;试验发现Sr虽然不能细化初晶硅,但对初晶硅有明显的裂解作用;P和RE复合变质使得初晶硅尺寸减小到25μm,而加入Sr后,由于Sr对初晶硅的裂解作用,使得初晶硅的尺寸减小到15μm,共晶硅大部分呈蠕球杆状或团球状,均匀弥散分布;试验得到了一种初晶硅和共晶硅细化效果均良好的复合变质剂。

Influences of P, Sr and RE Modifier on Microstructure of Hypereutectic Al-Si Alloy

Influences of single phosphorus,strontium,rare earth and mixed modifier on the microstructure of hypereutectic Al-Si alloy were studied.The results show that phosphorus modifications can refine primary silicon and strontium and rare earth react on the eutectic silicon.RE can also refine primary silicon quite a bit.The test indicates that strontium can break up primary silicon rather than refine it.Complex modification of phosphorus and rare earth decreases primary silicon within the range of 25 μm.With the adding of strontium to the complex modifier,the range of the primary crystal silicon can decrease to 15 μm.Moreover,the eutectic crystal silicon is well fined,dispersed uniformly in vermicular rod.An efficient modification agent is found.