In this study, in-situ aluminum matrix composites were synthesized through pyrolysis of high temperature vulcanization (HTV) silicone in aluminum melt. For this purpose 1 to 4 wt% of HTV silicone was added to a vortex of molten aluminum at 750 ° C and the resulting slurries were cast in steel dies. Consequently, microstructure, hardness and tensile properties at ambient and high temperatures of the as cast samples were examined. The results revealed in-situ formation and distribution of reinforcement particles in the matrix. EDS analysis indicated that the formed reinforcement particles were consisted of O and Si elements. This confirms the in-situ occurrence of pyrolysis and reinforcement formation. The size of the in-situ formed particles was mostly in 0.2 to 2 micrometers range. It was shown that the composite synthesized by addition of 4 wt% HTV had the highest mechanical properties both at ambient and high temperature. Room temperature hardness, tensile strength and yield strength of his sample were increased by about 50%, 23% and 19% compared to the monolithic sample, respectively. Keywords: aluminum matrix composite, in-Situ, pyrolysis, (HTV) silicone, ceramic reinforcement, mechanical properties, microstructure
