Microstructure of particle Reinforced Metal Matrix Composites produced by Centrifugal spray Forming Process

초록

Aluminium-Silicon alloy(JIS-AC8A) matrix composites reinforced with SiC particles(10% in vol.) were fabricated by centrifugal spray forming process, and the microstructure of the powders and the preforms produced were investigated. Aluminium alloy droplets solidified during flight show fine well defined dendrific structures, but the pre-solidified droplets of aluminium alloy reinforced with SiC particlates exhibit fine equiaxed grain structures. Eutectic silicon is crystallized at the corner of the fine aluminium grains, and some SiC particles seem to act as nucleation sites for pro-eutectic silicon during solidification of aluminium alloy. Such pro-eutectic silicon during solidification of aluminium alloy. Such pro-eutectic silicon seem to retard grain growth during spray forming process. The microstructure of composite powders formed by centrifugal spray forming process exgibit particle embedded type, and result in dispersed type microstructure in preforms deposited. The deposited preform of SiC reinforced Al-Si alloy MMC exgibits finer equiaxed grain structure than that of unreinforced Al-Si alloy.