Fullerene/A5083 composites fabricated by material flow during friction stir processing

Fullerene was successfully dispersed into A5083 by friction stir processing (FSP). Dispersion of the fullerene enhanced the grain refinement by recrystallization during the FSP and the grain size reached ∼200 nm. The hardness was also remarkably increased by both the grain refinement and the dispersion of the fullerene molecules. In this study, material flow during the FSP was investigated with respect to the dispersion of the fullerene. It was revealed that the formation mechanism of the “onion ring” was closely related to the convectional flow induced by the shoulder of the rotating tool. This material flow by the shoulder is very important when fabricating the surface composites by the FSP in order to provide a uniform dispersion of the reinforcement.