Effect of microstructural features on the ageing behaviour of Al–Cu/SiC metal matrix composites processed using casting and rheocasting routes

Abstract

In the present study, microstructural variation in Al–2 wt% Cu/SiC composites was accomplished by synthesizing them using conventional casting and partial liquid phase casting (rheocasting) routes. Microstructural characterization studies conducted on the rheocast composite samples revealed a finer grain size, minimal porosity, uniform distribution of SiC particulates, and a superior matrix – particulate interfacial integrity when compared to the conventionally cast composite samples. Furthermore, the results of interfacial characterization studies revealed that the presence of porosity associated with either individual SiC particulate or SiC clusters significantly influence the constitutional characteristics of the interfacial region. Results of ageing studies revealed an accelerated ageing kinetics in case of rheocast samples when compared to the conventionally cast composite samples. The results of ageing studies were finally rationalized in terms of the difference in microstructural characteristics of the rheocast and conventionally cast composite samples.