Abstract:  The microstructure, fracture morphology, and mechanical properties of both squeeze cast and subsequently isothermally extruded SiC_w/ZK51A magnesium matrix composite were experimentally investigated by means of transmission electron microscopy, scanning electron microscopy, and tension test respectively. The results show that the asextruded composite possesses much higher mechanical properties than the ascast composite, especially modulus of elasticity and mechanical strength. The main reason for this lies in that the extrusion deformation not only helps to improve the whisker/matrix interfacial bonding and to eliminate casting defects, but also makes the SiC whiskers tend to align uniformly and quasiunidirectionally in the extrusion direction, leading to excellent reinforcing effect by load transfer.

Key words: SiC whisker； ZK51A magnesium alloy； metal matrix composite； extrusion; microstructure and mechanical properties