Effect of Isothermal Forging on Fracture Toughness of SiC Particle Reinforced Aluminum Matrix Composite

20%SiCp/2009Al composites fabricated by powder metallurgy (PM) method were processed by isothermal forging, and the effects of different deformation on microstructure and mechanical properties were studied by optical microscopy, scanning electronic microscopy (SEM), tensile and fracture toughness testing. The results show that with the total strain increasing, distribution of SiC particles becomes uniform, the intensity and plasticity are significantly improved. The crack propagation paths of fracture toughness were observed by SEM. The main crack occurs in the aluminum matrix where SiC particles are agglomerated. The fracture mode of the composites combines toughness fracture of the matrix and particle brittle fracture.