Evaluating the microstructure evolution and wear behavior of friction stir processed aluminum matrix surface composites with nano-sized SiC particles

Abstract

In this research, Al6061 matrix composites were prepared via friction stir processing (FSP) to investigate the effect of incorporation of nano-SiC particles on dynamic recrystallization (DRX) and wear behavior. The microstructure was evaluated using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM), respectively. Wear and microhardness testing were performed on the various samples to investigate the differentiation. The results illustrated that the percentage of subgrain boundaries diminished from 46.5% to 27.9% drastically, and the counterpart to high angle grain boundaries (HABGs) enhanced from 48.8% to 65.4% in the composite compared with FSPed Al. It was also determined that 94% grain comprised of recrystallized grains in the composite. The results also indicated that the specific wear rate had a clearly consistent relationship with the increasing microhardness. It was found that the addition of nano-SiC not only accelerated DRX, but also exerted a more significant hindering effect on the growth of recrystallized grains owing to the pinning effect and shear effect, hence, reducing the grain size. The primary wear mechanism of the base metal and FSPed Al was adhesive wear, while that of the composite was abrasive wear in the present work.