Influence of processing parameters on the near-net shape synthesis of aluminium-based metal matrix composites

Abstract

The influence of the processing parameters on the near-net shape synthesis of Al–SiC particulate reinforced metal matrix composites (MMCs) by the disintegrated melt deposition (DMD) technique has been investigated. This novel processing method involves mixing the SiC reinforcement with the liquid Al matrix aided by mechanical agitation. The resulting composite slurry is then disintegrated by jets of inert gas and subsequently deposited on a metallic substrate. The processing parameters that were investigated include stirring speed during reinforcement addition, holding and stirring times following reinforcement addition and total flight distance. The resultant volume fractions of porosity and reinforcement in the composites were estimated by density measurement and chemical dissolution. Maximum incorporation of the reinforcement was achieved by dispersing the SiC particles in the liquid Al with an impeller at a stirring speed of 500 rpm. Composite porosity levels were minimized for holding and stirring times after SiC addition of 15 and 5 min, respectively, and for a total flight distance of 450 mm. The results obtained clearly demonstrate the dependence of the porosity levels on the total flight distance and the holding and stirring times and reinforcement incorporation on the stirring speed.