The interfacial characteristic of SiCp/AZ91 magnesium matrix composites fabricated by stir casting

The particle/matrix interfaces in SiCp/AZ91 composite fabricated by stir casting were investigated using transmission electron microscope (TEM) equipped with ultra-thin window energy dispersive X-ray analysis (EDAX) system. Chemical reactions indeed occurred at the interfaces. According to EDAX results, the interfacial reaction products are considered to contain Al₄C₃, MgO, and Mg₂Si phases. The interfaces can be classified into three types (interfaces I, II, and III) according to morphological features of the interfaces: (1) for interface I, interfacial reaction products were in direct contact with the surface of SiCp; (2) for interface II, interfacial reaction products were not in direct contact with the surface of SiCp; (3) for interface III, interfacial reaction products were not observed at the interfaces, i.e., interface III was simply formed by the two surfaces of SiCp and matrix. Mg₁₇Al₁₂ and Al₈Mn₅ precipitate phases heterogeneously nucleated at the particle/matrix interfaces.