Al-Mg/ (Gr+SiCp) composite material test specimens and gears using the liquid based stir casting process. The three particle sizes (10µm, 35µm and 65µm) and two weight fractions (5 and 10) of silicon carbide particle were reinforced in to the Al6061 and 2.8 wt. % of magnesium matrix metal alloy. Graphite was also added before the stirring to increase the wear resistance of the material during turning and hobbing of gear blanks. The fracture toughness was evaluated using Charpy impact test (ASTM E23 standards). The Charpy impact test was carried out for understanding the influence of SiC reinforcement with Al/Mg alloy. The results shows that reinforced aluminium matrix composite material having highest fracture toughness with lower contribution of ceramics SiC and increased in particle size than other composition.