Surface modification of aluminum alloy by incorporation of AlCoCrFeNi high entropy alloy particles via underwater friction stir processing

AlCoCrFeNi high entropy alloy (HEA) particles were incorporated into AA5083 matrix by underwater friction stir processing (UFSP) to modify the surface properties of aluminum matrix. The effects of incorporation of HEA particles on microstructural evolution, micromechanical properties and wear performance were investigated. Microstructural observations showed that HEA particles were homogeneously distributed in the matrix with refined grains, the interface between the HEA particles and matrix showed a good metallurgical bonding with the thickness of approximately 200 nm. The incorporation of HEA particles can effectively accelerate the dynamic recrystallization (DRX) due to particle stimulated nucleation (PSN) mechanism and result in higher fraction of high-angle grain boundary (HAGBs). The fabricated composite showed 68.8% higher microhardness compared with as-received Al. Nanoindentation test results showed that the hardness, elastic modulus, H/E and H3/E2 ratios of the matrix were also improved. The wear test results showed that the fabricated composite exhibited the lowest friction coefficient and wear loss in all samples, and the wear rate was decreased by 48.6% compared with that of the as received Al.