Abstract:SiC_p/2024 aluminum matrix composite plates were prepared by stir casting and hot extrusion process. The microstructures and mechanical properties of the as-cast, as-hot extruded and as-heat treated SiC_p/2024 aluminum matrix composite were investigated. The results show that SiC particles distribute uniformly in the as-cast composite ingot, most of which distribute along the grain boundaries, few locate inside the grains, the coarse secondary phases along the grain boundary distribute in discontinuity. After the hot extrusion process, most of the casting defects in the as-cast composite are eliminated. The broken eutectic phases and SiC particles distribute along the flowing direction of the metal plastic. The strength and ductility of SiC_p/2024 aluminum matrix composite increase obviously after hot extrusion. Under the condition of (495 ℃, 1 h)+(177 ℃, 8 h), the strength of the as-extruded composite plates can reach 430 MPa, S′(Al₂CuMg) phase is the main precipitate at this stage. The tensile fracture surface results show that the hot extrusion deformation is helpful to improve the bonding of the SiC/Al interface. The main fracture manner of SiC_p/2024 aluminum matrix composite after heat treatment is ductile failure of the alloy matrix, SiC fracture and debonding of the SiC/Al interface.

Key words: aluminum matrix composite; stir casting; hot extrusion; microstructures; mechanical properties