SIC/AL4C3 INTERFACES IN ALUMINUM SILICON-CARBIDE COMPOSITES

In transmission electron microscopy examinations of cast Al matrix-SiC particulate composites, it was noted that a coating of Al4C3 had been formed in contact with some SiC particles. The observed epitaxial orientation relationships at the SiC/Al4C3 interface and between the carbides and interfacial Al formed by Al4C3 decomposition are described. The lattice matching between SiC, Al4C3, and reprecipitated Al particles may result in strong bonding and thus permit crack propagation across such interfaces, contributing to the detrimental effects on fracture and fatigue associated with the presence of Al4C3 in aluminum-silicon carbide composites,