Study on microstructure evolution and wear resistance behavior of <i>in-situ</i> graphene reinforced aluminum matrix composites prepared via friction stir processing

Abstract In-situ graphene reinforced aluminum matrix composites (AMCs) were synthesized by friction stir processing (FSP) using Al5052 alloy and nano-graphite as raw materials. The microstructure, phase composition and wear resistance of AMCs were investigated to elucidate its wear resistance mechanism. The results show that the incorporation of nano-graphite resulted in significant grain refinement of AMCs, with 80.7% of the grain boundaries dominated with high-angle grain boundaries, and 93.2% of the grains were recrystallized grains. The intense shear effect generated in FSP caused the generation of few layers of wrinkled graphene, with the Al 4 C 3 phase detected at the edge. The microhardness of AMCs increased by about 50% and 27% compared to Al5052 base metal (BM) and FSPed Al, respectively. Besides, the average friction coefficient and specific wear rate of AMCs were minimum, which were 0.57 and 15.6 mm 3 (N·m) −1 , respectively. The specific wear rate of AMCs was reduced about 64.9% as compared to BM, while AMCs were mainly subjected to abrasive wear. The optimal wear resistance of AMCs is due to the dramatic increase in hardness as well as the self-lubricating effect caused by nano-graphite.