An experimental study was conducted to evaluate fracture toughness of metal matrix composite (MMC) analysis by heat treatment processes. The material was a 7.5 mm thick extrusion of 2124 aluminum alloy with 10 % SiC particulates. Fractographic examinations shows that failure occurred by the micro-mechanism involved with plastic deformation although the specimens broken by brittle fracture. Fracture toughness values depend upon the homogeneous distribution of the SiC particulates and its grain size. The observed K1c value is optimized by Taguchi technique by using 7.5 Design Taguchi software.