Investigation of microstructures and mechanical properties of ultrafine SiC reinforced pure Al matrix composites

Al based composites reinforced by 15vol% ultrafine SiC particles were fabricated using 800 nm sized SiC particles as the raw materials. The effects of the sintering temperature and severe compression treatment on the microstructures and mechanical properties of the composites were investigated. The results indicate that increasing the sintering temperature can effectively accelerate the densification of the composites. Compared to the composite sintered at 520 , the composite sintered at 610 has higher density, lower porosity and higher hardness. The hardness (HB) of the composite sintered at 610 is 83.9 HBS, much higher than that (53.7 HBS) of the composite sintered at 520 . This is due to the fact that increasing the sintering temperature can accelerate the atom diffusion, and thus help the consolidation of the Al powders, and Al powder and SiC powder to improve the interfacial bonding. It has also been shown that severe compression treatment can effectively increase the density of the composites and decrease the volume fraction of the pores. The density of the composite prepared by sintering under 610 and severe compression treatment is 2.68 g/cm3, which is very close to the theoretic density of the composite (2.78 g/cm3). The hardness of the composite can reach 121 HBS, and the tensile strength, yield strength and ductility can reach 177.6 MPa, 168.6 MPa and 3.97%, respectively. © 2015, Central South University. All right reserved.