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

In this study, aluminium-based metallic matrices with varying amount of cop per (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 inves tigation showed smaller sized and higher weight percent of SiC particulates being successfully incorporated with a decrease in the weight percent of c opper 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. Res ults of the microstructural characterisation studies also exhibited the pre sence 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 particul ates. The result of the ageing studies revealed an accelerated ageing kinet ics for the Al-1%Cu/SiC composite when compared to the Al-4.5%Cu/SiC compos ite samples. The results of accelerated ageing kinetics were rationalised i n terms of the effect of variation in the physical properties of the metall ic matrix and the ensuing microstructural characteristics due to variation in the amount of copper in the matrix. (C) 1999 Kluwer Academic Publishers.