THE QUASI-STATIC FRACTURE-BEHAVIOR OF AN ALUMINUM-ALLOY METAL-MATRIX COMPOSITE

A study has been made to understand the microstructure, tensile deformation and fracture characteristics of an aluminum alloy 2080, discontinuously-reinforced with varying amounts of silicon carbide particles. Results reveal the elastic modulus and strength of the metal-matrix composite increase with an increase in reinforcement content in the metal matrix. The increased strength of the Al/SiCp composite is ascribed to the competing and synergistic influences of residual stresses generated as a result of intrinsic differences in thermal expansion coefficients between the composite constituents and strengthening from constrained plastic flow and triaxiality in the ductile matrix which is due to the presence of hard and elastically deforming reinforcements. Fracture on a microscopic scale comprised cracking of the individual and clusters of particules present in the microstructure, Particle cracking increased with reinforcement content in the aluminum alloy matrix. Final fracture of the composite resulted from crack propagation through the matrix between particulate clusters. The intrinsic mechanisms and micromechanisms contributing to strength and governing the tensile fracture process are discussed.