(1. 重庆大学 材料科学与工程学院，重庆 400044；
2. 重庆大学 电子显微镜中心，重庆 400044；
3. 包头稀土研究院，包头 014030)
摘 要: 采用金相显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和差示扫描量热法(DSC)等研究不同含量稀土Sm对Al-7Si-0.3Mg合金微观组织的影响。结果表明：添加Sm元素之后，合金的二次枝晶间距相比基础合金的明显减小；稀土Sm可以显著细化片层状的共晶硅，Sm元素主要形成Al2Si2Sm相。从能量角度，Sm可优先与P形成SmP相，可能会抑制AlP相的形成，减弱其促进共晶硅形核的效能。随着Sm元素含量的增加，Al-Si共晶反应的过冷度逐渐增大。
关键字: Al-7Si-0.3Mg铝合金；稀土Sm；微观组织；细化机理
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2. Electron Microscopy Center, Chongqing University, Chongqing 400044, China;
3. Baotou Research Institute of Rare Earths, Baotou 014030, China）
Abstract:The effect of different contents of rare earth Sm on the microstructure of Al-7Si-0.3Mg alloy was investigated by using multiscale microstructure characterization techniques (i.e., OM, SEM, TEM), XRD and DSC analyses. The results show that the secondary dendrite arm spacing in the Al-7Si-0.3Mg is significantly reduced by Sm addition. Plate-like eutectic Si is refined obviously. Sm is mainly consumed through the formation ofAl2Si2Sm phase. According to the formation energy, the SmP phase easily forms, which could inhibit the formation of AlP phase, and deteriorate the function of AlP phase to eutectic Si in Al alloys. The undercooling of the Al and Si eutectic reaction increases with increasing the Sm content.
Key words: Al-7Si-0.3Mg aluminum alloy; rare earth Sm; microstructure; refining mechanism
