The primary purpose of this research is to investigate the effect of green sand mold, CO{sub}2 mold and permanent mold on the microstructure and mechanical properties of 12wt% SiC/A356 composites. Commercially A356 alloy were selected as the matrix for the composites. The reinforcement particulates are high purity silicon carbide with an average diameter of 80μm. Processing of the composites, which consists of mixing preheated SiC particulates with molten A356 alloy, melt stirring and composites casting, The result showed that for all three casting method employed, the ultimate tensile strength and the Vickers's hardness by using pemanent mold (176.01MPa, Hv94.7) is higher than that of using green mold (121.15MPa, Hv77.9) and CO{sub}2 mold (112.52MPa, Hv71.8 )at the same casting conditions. One of the main factors is the cooling rate of green sand mold or CO{sub}2 mold slower than permanent mold, at a microscale level, clustering is observed because the reinforcement particles have been pushed out by dendrite and dendrite arm space (DAS) is increase.
SiC
/A356 composites Casting method Mechanical properties Dendrite Pushing