Corrosion and diffusion barrier behavior of NiAlY/AlCrTaTiZr coating in dry CO₂ atmosphere at 650 °C: Experimental study and first-principles calculation

In this work, NiAlY coatings with and without AlCrTaTiZr high entropy alloy diffusion barrier were deposited on Fe–Cr alloy by magnetron sputtering, and their corrosion and interdiffusion behavior are investigated systematically at 650 °C in dry CO₂ gas. The results show that the corrosion rate constant and the thickness of the interdiffusion zone of composite coating are both smaller than those of NiAlY coating after 300 h. Moreover, no harmful brittle intermetallic FeAl₃ precipitates in composite coating, and internal oxidation phenomenon can not occur. Based on first-principles calculations, it is suggested that the HEA layer of the composite coating effectively slows down the diffusion of Al and Ni atoms in the HEA phase and inhibits the interface diffusion of HEA/Fe. The addition of AlCrTaTiZr HEA enhances the high-temperature anticorrosion property of the NiAlY coating.