Deformation and fracture behavior of cast and extruded 7075Al-SiCp 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 SiCp 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% SiCp showed linear increases in the Young's Modulus values with a maximum increase of 78% for the 32 vol% SiCp 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% SiCp, respectively. The elevated temperature tensile tests indicated high strength retention ability of the composites up to 250 degrees C. Room temperature strain to failure values for the base alloy dropped substantially when reinforced with SiCp. However, the strain to failure values for composites increased with increase in test temperatures and the 32 vol% SiCp composite showed a strain to failure value of 9.5% at 350 degrees C almost equal to the room temperature strain to failure value for the base alloy