In the present work Al356/SiC p composites were produced by stir casting and compocasting techniques. SiC particles were injected into the melt in three forms of SiC p powder or (Al-SiC p ) and (Al-SiC p -Mg) composite powders. The composite powders were produced by low energy ball milling of SiC p , Al and Mg powders. The effects of the type of the injected powder and the casting method on the porosity, microstructure, distribution and incorporation of the reinforcement particles as well as their macro- and micro-hardness, wear resistance, tensile properties in low and high temperatures, impact strength and three point bending strength were investigated. The results revealed that addition of SiC p particles in the form of composite powders and casting in semisolid state decreased the SiC p particle size, porosity and grain size, enhanced the wettability between the molten matrix alloy and the reinforcements and improved the distribution of the reinforcement particles in the solidified matrix. Simultaneous utilization of the advantages of injection of (Al-SiC p -Mg) composite powder and semi solid processing reduced the porosity content of the cast composites by 78% and increased their incorporated reinforcement by about 83%. As a result, macro- and micro-hardness and tensile properties of the composites were also increased. Elastic modulus, yield strength, ultimate tensile strength and elongation of the composites produced by injection of composite powders was significantly improved compared with the matrix alloy or the composite produced by injection of untreated SiC p . While the un-reinforced alloy kept less than 70% of its strength at 300?C, the composites samples kept more than 90% of their strength at this temperature. The impact energy and bending strength of all composite samples were reduced compared to those of the matrix alloy but the reduction was less significant for the composites manufactured by injection of composite powders or treatment in semi-solid temperature range. Furthermore, different possibilities for melting of the injected particles of the composite powders and distribution of SiC p in the melt were envisaged and the consequences were discussed considering the possibility of the oxide film on the particles hindering the distribution of the reinforcements.
