稀土Pr对过共晶Al-18%Si-Mg合金组织与性能影响的研究  

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

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：《铸造》2007年第1期26-30,共5页Foundry

摘　　要：采用扫描电镜观察了不同稀土Pr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Pr对Mg2Si相结晶行为及合金性能的影响。试验结果表明:在未完全变质合金中Mg2Si相以网状或骨骼状形式存在,与共晶Si片之间存在附着生长关系;而完全变质合金中,Mg2Si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Mg2Si相凝固结晶行为及合金性能产生了重要影响,这与初晶Si和共晶Si的变质程度有关。SEM was used to observe the changes of the microstructure in hypereutectic Al-18% Si-Mg casting alloys with varying rare earth additions. At the same time, the effect of rare earth on the crystallizing behavior of Mg2i phase and mechanical properties were discussed. It is found that： Mg2i phase nucleates on the surface of the eutectic Si flakes in the un-fully modified alloys, growing as net or skeleton shape, however, very few and fine Mg2Si particles are isolated at the boundaries of eutectic cells in the fully modified alloys. Rare earth plays an important influence on the crystallizing behavior of Mg2Si phase in Al-Si-Mg casting alloys and their mechanical properties. It is thought to be related to the amount of the modification of a（Si） and eutectic Si phases.

关 键 词：过共晶 铝镁硅合金 稀土变质 MG2SI 

分 类 号：TG113[金属学及工艺—物理冶金]