Deformation and Fracture Behavior of Cast and Extruded 7075Al-SiC<I><SUB>p</SUB></I> Composites at Room and Elevated Temperatures

Abstract

Casting of particulate reinforced Metal Matrix Composites has gained popularity due to inherent advantages like isotropic properties, ease of fabrication and a lower cost. The aim of the present study is to explain the tensile behavior at room and elevated temperatures of 7075 Al reinforced with varying amounts of SiC p by a casting route followed by extrusion. Microstructural characterization of as cast specimens has revealed the presence of second phases and reaction products at the particle-matrix interface. Tensile results for the extruded and peak aged composites containing 13, 21 and 32 vol% SiC p showed linear increases in the Young's Modulus values with a maximum increase of 78% for the 32 vol% SiC p composite over the monolithic alloy. An improvement of 18%, 41% and 9.4% in yield strength resulted on reinforcing the 7075 Al alloy with 13, 21 and 32 vol% SiC p , respectively. The elevated temperature tensile tests indicated high strength retention ability of the composites upto 250°C. Room temperature strain to failure values for the base alloy dropped substantially when reinforced with SiC p . However, the strain to failure values for composites increased with increase in test temperatures and the 32 vol% SiC p composite showed a strain to failure value of 9.5% at 350°C almost equal to the room temperature strain to failure value for the base alloy.