Effect of variation in physical properties of the metallic matrix on the microstructural characteristics and the ageing behaviour of Al-Cu/SiC metal matrix composites

Abstract

In this study, aluminium-based metallic matrices with varying amount of copper (1 wt% Cu and 4.5 wt% Cu) were reinforced with SiC particulates using a partial liquid phase casting technique. The results of the present investigation showed smaller sized and higher weight percent of SiC particulates being successfully incorporated with a decrease in the weight percent of copper in the matrix. Microstructural characterisation studies conducted on the composite samples revealed an increase in uniformity of distribution of SiC particulates, improved SiC/Al interfacial integrity and smaller grain size of the metallic matrices with decreasing weight percent of copper. Results of the microstructural characterisation studies also exhibited the presence of solute rich zone in the near vicinity of SiC particulates and the nucleation of secondary phases both at and in near vicinity of SiC particulates. The result of the ageing studies revealed an accelerated ageing kinetics for the Al-1%Cu/SiC composite when compared to the Al-4.5%Cu/SiC composite samples. The results of accelerated ageing kinetics were rationalised in terms of the effect of variation in the physical properties of the metallic matrix and the ensuing microstructural characteristics due to variation in the amount of copper in the matrix.