High-resolution TEM characterization of SiC nanowires as reinforcements in a nanocrystalline Mg-matrix

SiC nanowires have been used as potential reinforcements in a nanocrystalline magnesium-based matrix composite processed by cryomilling and spark plasma sintering. The morphology and crystallinity of SiC nanowires were studied by scanning and transmission electron microscopies. Our results indicate highly faceted sidewalls and bamboo-like SiC nanowires that contain a high density of twins and stacking faults. In addition to the common cubic 3C crystal structure, we also found the hexagonal 2H polytype. We suggest that the particular morphology of the SiC nanowires enhances their interlocking with the Mg matrix. A detailed analysis of the interface between a SiC nanowire and the nanocrystalline magnesium alloy was performed using high-resolution transmission electron microscopy and energy dispersive spectroscopy techniques. We demonstrate the absence of interfacial reaction at the SiC nanowires/Mg-matrix interfaces, which is critical for the development of high-performance composites.