Influence of silicon carbide particulate reinforcement on the Fracture toughness of Al 6061 alloy composites produced by stir casting method

In this paper, the Fracture behavior of Al6061 alloy, discontinuously reinforced with fine particles(25μm) of silicon carbide are presented and discussed. The discontinuously reinforced aluminium (DRA) alloy composites with 10% and 15% volume fraction of particulates were produced by the stir casting method and using them test specimens were prepared as per ASTM standard. Heat treatment was done for the test specimens at different solutionising time, aging time and aging temperature. The room temperature Fracture toughness (K_1C) values were found for all test specimens using universal testing machine. The results show that reinforcement of the metal matrix with silicon carbide particles up to a volume fraction of 15% decreases the K_1C. The heat treatment conditions were optimized by Taguchi method for obtaining maximum value of K_1C for the composites. Among the several process parameters, the aging temperature is found to contribute more to the increase in Fracture toughness. The scanning electron micrographs of the fracture surface of 10% and 15% vol. SiC_p composites show the ductile tear ridges and cracked SiC particles indicating both ductile and brittle fracture mechanism.