Abstract:The influences of SiC content on the microstructure, porosity, hardness and wear resistance of A356-SiC_p composites processed via two different methods of compocasting and vibrating cooling slope (VCS) were compared with each other. In the as-cast condition, the matrix of VCS and compocast processed composites exhibited globular and dendritric structures, respectively. While a more uniform distribution of SiC particulates in the matrix alloy as well as higher hardness values were obtained for the VCS processed samples, the composites produced via compocasting exhibited less porosity. The increased SiC content (up to 20% in volume fraction) resulted in a more uniform distribution of SiC particles within the matrix alloy and improved wear resistance for both the composite series. However, for the VCS processed composites, the increased SiC content, resulted in the decreased size and shape factor of globules as well as better tribological properties when compared with compocast composites. It was concluded that the improved properties of the VCS processed composites when compared with their compocast counterparts was a consequence of a more uniform distribution of SiC particulates in the matrix alloy as well as the globular microstructure generated during the VCS process.

Key words: Al-A356/SiC_p composite; compocasting; vibrating cooling slope; microstructure; particle distribution; porosity; hardness; wear resistance