Effect of Hot Extrusion on Interfacial Microstructure and Tensile Properties of SiCp/2009Al Composites Fabricated at Different Hot Pressing Temperatures

The effects of hot extrusion on the interfacial microstructures and tensile properties of 15 vol.% SiCp/2009Al composites fabricated at different hot pressing temperatures were investigated. After hot extrusion, the relative density of the composites increased, the SiC particle distribution became more uniform, and the SiC particles tended to align along the extrusion direction. Furthermore, the interface bonding was improved after hot extrusion; however, the extrusion exerted no obvious effect on the interfacial reaction products formed during sintering process. Tensile tests indicated that the mechanical properties of the composites were improved significantly after extrusion. Fractography revealed that the fracture mechanism of the extruded composites fabricated at the hot pressing temperatures below 540°C was mainly the interfacial debonding. For the extruded composites fabricated at 560-600°C, the fracture was the matrix ductile fracture and the SiC particle fracture. When the composites were hot pressed at or above 620°C, after extrusion, the fracture mechanism of the composites was the matrix ductile fracture, the interface cracking and the SiC particle fracture.