Carbon fiber reinforced AZ91 D matrix composites with pyrolytic(PyC) coating deposited on fiber surface(PyC-C_f/AZ91 D composites) have been fabricated by Liquid-solid extrusion following vacuum pressure infiltration technique(LSEVI). Interfacial microstructure and failure behavior of the composites were investigated. Instead of interfacial reaction products, block-shaped interfacial precipitates Mg_(17) Al_(12) were detected at the interface, which indicates that interfacial reaction was restrained by LSEVI and PyC coating. Nano-MgO was detected at the interface. Interfacial failure behavior of the PyC-Cf/AZ91 D composites,which was the failure between PyC coating and AZ91 D alloy due to the mismatch of thermal expansion and relatively poor bonding, was proposed. Fracture surface of the PyC-C_f/AZ91 D composites was characterized by fibers pulling-out tests. PyC coating served not only as protection to the fibers, but also an adjustment of the interface of the composites.
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