In this work AA6063-Silicon carbide composites were fabricated using conventional stir casting. Agglomeration of reinforcement particles which is a serious drawback in conventional stir casting was attempted to be reduced by applying ultrasonic waves to the composite melt after mechanical stirring. The composites were fabricated with different weight percentages (2,4,6 and 8\%) of SiC particles having 10 mu m average particle size. The mechanical properties of the composites were evaluated for both the cases and were compared to study the influence of ultrasonic waves. It was found that the mechanical properties of the composite increased with increase in the weight percentage of the reinforcement up to 4 wt\% SiC and reduced beyond that. The 4 wt\% SiC stir cast composite subjected to ultrasonic waves showed 51.17\%, 67.52\% and 38.31\% increase in ultimate tensile strength, yield strength and hardness respectively when compared to the base alloy.