稀土变质处理对过共晶Al-18%Si-Mg合金组织和性能的影响  

Influence of Rare Earth Modification on Microstructure & Mechanical Properties of the Hypereutectic Al-18%Si-Mg Casting Alloys

作　　者：刘萍[1] 

机构地区：[1]上海交通大学材料科学与工程学院,上海200240

出　　处：《机械工程材料》2007年第5期36-40,共5页Materials For Mechanical Engineering

摘　　要：采用扫描电镜观察了不同稀土加入量变质处理过共晶Al-18%Si-Mg合金的组织变化,并分析了稀土对Mg_2Si相结晶行为及合金性能的影响。结果表明:在未完全变质合金中Mg_2Si相以网状或骨骼状形式存在,与共晶硅片之间存在附着生长关系;而在完全变质合金中,Mg_2Si相以细小的颗粒相形式孤立地存在于共晶团边界上,数量极少。稀土的存在对Mg_2Si相凝固结晶行为及合金性能产生了重要影响,这与初晶硅和共晶硅的变质程度有关。SEM was used to observe the changes of the microstructure in hypereutectic Al-18wt% Si-Mg casting alloys with＇various rare earth additions. The effect of rare earth on the crystallizing behavior of Mg2 Si phase and mechanical properties were discussed. Mg2 Si phase nucleated on the surface of the eutectic Si flakes in the unfully modified alloys, growing as net or skeleton shape, however, very few and fine Mg2 Si particles were isolated at the boundaries of eutectic cells in the fully modified alloys. Rare earth had an important influence on the crystallizing behavior of Mg2 Si phase in Al-Si-Mg casting alloys and their mechanical properties. This thought to be related to the amount of the modification of α （Si） and eutectic Si phases.

关 键 词：过共晶 铝镁硅合金 稀土变质 MG2SI 

分 类 号：TG146.2[一般工业技术—材料科学与工程]