Nanoparticulates reinforced aluminum metal nanocomposites are prospective materials for aerospace, automobile, sports, and marine industries because of their superior strength to weight ratio and high temperature bearing properties. In this work, novel ultrasonication assisted casting method was used to fabricate different weight percentages (0, 0.5, 1.0 and 1.5) of SiC nanoparticulates reinforced aluminum alloy 6061 nanocomposites. The following results were observed from hardness test, impact test and grain size measurements. Increase in weight percentage of nano-SiC in aluminum matrix leads to significant improvement in microhardness, which was confirmed by Vickers-microhardness tests. Compared to the monolithic aluminum, the maximum improvement in microhardness of around 47 % was observed in 1.5 weight percentage SiC reinforced composites. Optical microscopic images showed refined aluminum grains in nanocomposites compared to pure alloy. Impact resistance of aluminum matrix was almost retained with an addition of SiC nanoparticles. Impact fracture surfaces of both pure alloy and nanocomposite exhibit the combination of ductile and brittle fracture.