Microstructures, high-temperature tribological and electrochemical mechanisms of FeCoNiCrAl high-entropy alloy coating prepared by laser cladding on a copper alloy: Combined TEM and DFT calculation

Two layers of FeCoNiCrAl coatings were prepared on copper (Cu) alloys substrates in this paper in order to improve the wear and corrosion performance of Cu alloys and to reduce the dilution of Cu in the laser cladding (LC) process. The microstructures, phase composition, microhardness, and crystal structure of the resulting coatings were analyzed, and their high-temperature tribological and electrochemical properties were tested. The results show that the surface of the HEA coatings still consists of a single-phase body-centered cubic (BCC) with low Cu content, and no generation of a second phase was observed. Compared with the substrate, the FeCoNiCrAl HEA coatings have better wear resistance, with oxidative wear and slight adhesive wear as the wear mechanism at 250 degree celsius. In addition, the FeCoNiCrAl HEA coating showed better electrochemical corrosion performance in 3.5 wt% NaCl solution. The corrosion mechanism is that the dense oxide layers inhibit the erosion of Cl-- and high reaction barriers slow down electrochemical reactions.