Flow behavior of SiC particles as tracer material during the fabrication of MMCs by friction stir processing

Abstract

Friction stir processing is a novel technique for metal matrix composites fabrication. During the friction stir process, the flow behavior of reinforced particles and base metal are very important. Very little is known about particle flow during fabrication of MMCs by friction stir processing, which is quite different from friction stir welding or friction stir processing without reinforced particles. The reinforced particles blocked the continuous flow of the base metal, significantly affecting the flow behavior. In this study, SiC particles were placed in different positions of the base metal before friction stir processing. The relationship between the initial positions and the final distribution of SiC particles was obtained. When the particles were put in middle layer of the plate and the rotation direction of the tool is opposite to the screw direction of the pin (counter-clockwise), the final distribution area is fairly large and uniform. This is the optimized position for making MMC’s by FSP. Bulk metal matrix composites were achieved by placing the reinforced material in this position. The MMC showed a uniform microstructure and excellent tensile properties.