Surface oxidation mechanism of CoCrFeNi high entropy alloy

High-entropy alloys (HEAs) are becoming increasingly important in advanced manufacturing applications due to their exceptional material properties, including oxidation resistance at and within extreme conditions. In this study, a combined experimental theoretical approach is used elucidate surface/near-surface details of structural, energetic, chemical/electronic properties CoCrFeNi, quaternary fcc HEA, upon exposure oxygen. Employing Density functional theory (DFT) calculation DFT-driven Molecular Dynamics (DFT-MD), as well photoelectron spectroscopy, we show strong evidence that, the oxygen coverages used, limited near-surface region random HEA that propensity Cr >> Fe ≈ Co Ni atoms, identified by an enhanced hybridization O 2p with 3d, lesser extent Co. Moreover, comparing interaction strength pure metal surfaces, there weakening Cr-O binding presence while Co-O stronger. Ni-O does not seem be affected, but being weakest interaction, binds Cr, Fe, little left bind Ni.