Mechanical properties of aluminum-matrix composites, fabricated by dispersion of fine SiC particulates of which size was less than 1㎛ into 2024 and 7075 aluminum alloys, have been investigated. Homogeneous mixing between the matrix and SiC particulates could be achieved by jar milling for 8hours with appropriate processing agent. At temperatures below 473K, high-temperature tensile strength of the composites was higher than that of the 2024 and 7075 aluminum alloys which were used as matrix materials. However, tensile strength of the composites was approximated to that of the matrix materials at 573K. Thus, it could be suggested that effects of particle dispersion on tensile strength of aluminum alloys was diminished at temperatures higher than 573K.