Influence of Al particles as infiltration promoters on the interfacial reaction and mechanical property of a continuous SiC fiber/AZ91 composite fabricated by a low-pressure infiltration method

Abstract

In this study, Mg alloy-based composites (MMC: metal matrix composite) with uniaxially oriented continuous SiC fibers were fabricated using a low-pressure infiltration method. Next, the influence of Al particles as the infiltration promoter on the interfacial reaction between the SiC fibers and the Mg alloy matrix was investigated by means of scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. In the presence of Al particles, β-Mg17Al12 was preferentially precipitated around the SiC fibers. The SiC fibers and the Mg alloy matrix did not react directly and remained bonded at the fracture surface. In contrast, in the absence of Al particles, whisker-like Al4C3 was observed around the SiC fiber, and a reaction phase consisting of MgO and Mg2Si was observed in the circumferential part inside the SiC fiber. The detachment occurred between the SiC fibers and the Mg alloy matrix at the fracture surface.