Synthesis, Tensile Testing, and Microstructural Characterization of Nanometric SiC Particulate-Reinforced Al 7075 Matrix Composites

This article examines the reasons for the poor performance of the nanometric scale SiC (n-SiC _p ) particulate-reinforced Al 7075 composites. The composites having different volume fractions of the n-SiC _p were synthesized via powder metallurgy (P/M) route and were uniaxially tested at room temperature. Experimental results showed a significant drop in the hardness and tensile properties of the composites in comparison with those of the monolithic Al. Microstructural analysis via scanning electron microscopy (SEM) revealed large segregation of Mg in the vicinity of the n-SiC _p and at the grain boundaries of the Al matrix, which plausibly changed both the aging kinetics and tensile behavior of the Al matrix. The segregation of Mg increased with an increase in the volume fraction of the n-SiC _p in the Al matrix. No Mg segregation was found in the monolithic Al. The clustering of the n-SiC _p was observed from SEM with energy dispersive X-ray analysis. SEM also revealed cracks in the n-SiC _p clusters and debonding between the clusters and Al matrix, which were considered as the main mode of fracture in the composites.