Microstructure evolution, wear resistance and corrosion resistance of CoCrCu0.5FeNiSix high-entropy alloy coatings fabricated by laser cladding

This study aims to thoroughly investigate the mechanisms by Si element affects the phase composition, microstructure, wear resistance, and corrosion resistance of high-entropy alloy coatings. CoCrCu 0.5 FeNiSi x (x = 0, 0.5, 1, 1.5, 2) high-entropy alloy coatings were fabricated on the surface of AISI 1045 steel using laser cladding technology. The experimental results indicated that Si promotes the formation of silicide phase and BCC phase. Additionally, the addition of Si encourages grain refinement and the transformation from columnar to equiaxed crystals. The microhardness of the CoCrCu 0.5 FeNiSi x high-entropy alloy coatings increased with the addition of Si. The average microhardness of the Si 2 coating reached 389.05 HV 0.5 , which is 2.33 times greater than that of the Si 0 coating (166.77 HV 0.5 ). As the Si content increased, the wear resistance of the CoCrCu 0.5 FeNiSi x high-entropy alloy coatings gradually improved. The average friction coefficient decreased from 0.9499 to 0.6285, and the wear rate decreased from 0.02913 mm 3 /N·m to 0.0146 mm 3 /N·m. The main wear mechanisms include adhesive wear, abrasive wear, and oxidative wear. The addition of Si enhanced the corrosion resistance of the CoCrCu 0.5 FeNiSi x high-entropy alloy coatings. In a 3.5 % NaCl solution at room temperature, the Si 2 coating exhibited the highest self-corrosion potential (−0.429 V) and the lowest self-corrosion current (1.15E-6 A/cm 2 ). EIS and M − S test results indicated that the passivation film of CoCrCu 0.5 FeNiSi x high-entropy alloy coatings had n-type semiconductor characteristics, and the passivation film of Si 2 coating was the most stable and dense. The findings provide practical guidance and theoretical support for fabricating high-performance high-entropy alloy coatings.