Study of Microstructure and Mechanical Properties of Short Carbon Fibers Reinforced Mg Matrix Composites Fabricated by Hot Extrusion

This study investigated the effect of extrusion ratio on the microstructural evolution and mechanical properties of the as-extruded short carbon fibers (SCFs) reinforced AZ31 alloy composite, and the microstructural development of the composite during extrusion was thoroughly investigated. The dominant dynamic recrystallization (DRX) mechanisms are particle simulated nucleation, continuous DRX, and discontinuous DRX. The addition of SCFs promotes the dynamic recrystallization during hot extrusion. As extrusion ratio increases, the interfacial bonding degree of the composite increases gradually, and the composite with an extrusion ratio of 25:1 exhibits the finest DRXed grains and the best mechanical performance with a yield strength of 171 MPa, an ultimate tensile strength of 258 MPa and an elongation of 6.0%. The enhanced strength is mainly attributed to grain refinement strengthening and dislocation strengthening, which are induced by the DRXed grains and the added SCFs.