Microstructure evolution and elemental diffusion of SiCp/Al–Cu–Mg composites prepared from elemental powder during hot pressing

Abstract

15vol%SiCp/Al–Cu–Mg composites were fabricated by hot pressing method using pure elemental powders. Microstructure evolution and elemental diffusion of Cu and Mg were studied. The microstructure of as-hot pressed composites and the elemental distribution of the composites before and after solution treatment were also investigated. The results showed that there were two types of eutectic liquid phases with different compositions after the compact was heated to 580 °C. After the compact was held at 580 °C for 60 min, the eutectic liquid was absorbed into the Al matrix and some equilibrium liquid phases formed in the boundaries of the initial Al particles. Meanwhile, Cu was homogeneously distributed in the Al particles while Mg tended to be distributed near the boundaries of the initial Al particles and in the SiC clusters. The presence of Al₂Cu, Mg₂Si, and some oxides of Mg was identified in the as-hot pressed composite. After solution treatment, Al₂Cu dissolved into the Al matrix, however, some Mg-rich compounds (silicide and oxide of Mg) did not dissolve into the matrix completely.