半固态Al-20Sn-1Cu轴承合金的制备及其组织分析

Preparation and Microstructure of Semi-solid Al-20Sn-1Cu Bearing Alloy

采用光学显微镜和扫描电子显微镜(SEM)对半固态方法制备的Al-20Sn-1Cu轴承合金的微观组织进行了分析。结果表明,Al-20Sn-1Cu轴承合金材料具有非常细小和均匀的组织。在铸件的整个断面上没有发现粗大的树枝Sn相和Sn相的偏聚。相组成主要由初生α-Al相、二次α-Al相和共晶Sn相组成。球形的初生α-Al相尺寸约为50μm。细小的共晶Sn相以连续的方式均匀地分布在晶界处,形成网状结构,该网状结构经后续的热处理变为细小弥散的Sn颗粒。

Microstructure of semi-solid Al-20Sn-lCu bearing alloy was observed by OM(optical microscope) and SEM(scanning electron microscope).The results indicate that the semi-solid Al-20Sn-lCu alloy possesses uniformly distributed fine microstructure,in which the absence of coarse dendrite Sn and Sn segregation can be observed.The phase constituent is composed of primary α-Al phase,sub-primary α-Al phase and eutectic Sn phase.The size of spheroidized primary α-Al phase is about 50 μm in equivalent diameters.The fine eutectic Sn phase is continuously uniformly distributed along the grain boundary,forming a network structure.However,the network structure in the alloy can be converted into fine Sn dispersoids after heat treatment at 623 K for 1 hour.