(东南大学 机械工程系， 南京 210018)
摘 要: 研究了在Sr变质的近共晶Al11.6%Si(质量分数)合金中加入混合稀土(MM)对组织的影响。 Sr对二次枝臂间距(DAS)起着重要的作用， 随着Sr含量的增加， DAS减小； 随着MM加入量的增加，枝晶 α 的数量增加， 主干长度缩短， 存在等轴化趋向， 但同时导致DAS增加，也导致共晶硅尺寸增大。 MM的加入在某种程度上削弱了Sr的变质作用。
关键字: AlSi合金； 锶变质； 混合稀土
（Department of Mechanical Engineering, Southeast University，Nanjing 210018, P.R.China）
Abstract:The effects of AlMM master alloy on the microstructures of neareutectic Al11.6%Si(mass fraction) alloys modified with Sr were investigated. Sr plays a crucial role in determining the DAS(second dendritic arm spacing) and the value of DAS decreases linearly with increasing Sr content in the melt. With the increase of MM addition, the amount of primary α increases, which inclines to become equiaxed, and DAS value and the size of eutectic silicon also increase. The addition of MM reduces the effectiveness of Sr modification to some extent.
Key words: AlSi alloy； Srmodification； mischmetal
