Microstructural Features, Corrosion and Wear Behavior of the AlCrFeCoNiCu High-Entropy Alloy, Electrodeposited Coatings, and Subsequent Heat Treatment

High-entropy alloy although having excellent corrosion and oxidation resistance properties, and thermal stability has always been debatable which is closely related to materials application questioning the performance of thin film at elevated temperature. Electrodeposition was carried out on mild steel substrate using AlCrFeCoNiCu high-entropy alloy (HEA) followed with heat treatment at 600 degrees C to study the morphological, corrosion, and tribological behavior of HEA coatings. Hardness study was correlated with the scratch test analysis to study the wear mechanism of the coatings. More fine globular structure with increase in phase fraction of obtained dual phase (FCC + BCC) suggested increase in hardness and decrease in surface roughness exposing lesser surface area for corrosive media attack resulting in enhanced corrosion performance of heat-treated coatings. A prolonged corrosion study showed highest polarization resistance values for heat-treated coatings for all the exposed time duration 6 h, 24 h, 48 h, and 72 h when compared to substrate and pristine sample. Decrease in crystallite size and increase in lattice strain induced higher hardness promoting severe lattice distortion effect. Hydrophobic nature of heat-treated coatings prevents the corrosive media attack forming a stable passive film (Cr2O3, NiO, and CuO) with protection efficiency of 76.35%.