Effect on Morphology and Corrosion Behavior of AlCrFeCoNi High-Entropy Alloy Coatings Prepared by Electroless Process on Mild Steel Substrate

The AlCrFeCoNi high entropy alloys (HEAs) coatings were prepared by electroless deposition process on mild steel (MS) substrates. Post annealing treatment at 600 °C for 30 min was carried out on coated HEA samples. The morphology, phase analysis, corrosion behavior, and surface oxide chemistry were observed for substrate, as coated HEA, and post-annealed samples. All the samples exhibited BCC phase formation with increasing BCC phase fraction. The HEA_2 (31.75 ± 2.6 μA/cm2) samples exhibited the lowest corrosion current density value (icorr) as compared to HEA_1 (75.2 ± 2.4 μA/cm2) and MS (135 ± 4.5 μA/cm2) which shows that HEA coatings can improvize the corrosion property of mild steel. Also, post annealing treatment of HEA coatings can enhance the corrosive resistant properties with uniform, globular, and homogeneous surface morphology. The formation of stable oxides Coox3+, Alox3+, and Crox3+ in HEA_2 led to more hydrophobic barrier protecting coatings as well as the substrate from corrosive media.