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The electrochemical corrosion behavior of Al0.5CoCrFeNi0.4high-entropy alloy (HEA) in 3.5 wt.% NaCl solution was investigated by electrochemical measurements coupled with comprehensive characterization of its surface films. The results demonstrate that the Al0.5CoCrFeNi0.4HEA primarily consists of (Al,Ni)-rich B2 phase and (Cr,Fe)-rich A2 phase. When subjected to electrochemical polarization, an ultrathin passive film rich in Cr is homogeneously formed on the surface. As the applied potential increases, the protective film tends to break down at the interface of two phases, followed by the preferential dissolution of B2 phase. Finally, the surface film with a triple-layer structure is formed on the HEA surface. Specifically, the inner layer and the middle layer are enriched in Cr and Fe, respectively, due to the high stability of Cr species and the selective dissolution of Fe. The (Al,Ni)-rich corrosion products are found to deposit at the outmost position ascribed to the dissolution of B2 phase.

The co-adsorption behaviors of SO2and H2O on face-centered cubic Cu (100) ideal surface were studied using the GGA-rPBE method of density functional theory (DFT) with slab models. The optimized structures of single H2O and SO2on Cu (100) surface were calculated at the coverage of 0.25 ML (molecular layer) and 0.5 ML. The results show that there was no obvious chemical adsorption of them on Cu (100) surface. The adsorbed structures, adsorption energy and electronic properties including difference charge density, valence charge density, Bader charge analysis and partial density of states (PDOS) of co-adsorbed structures of H2O and SO2were investigated to illustrate the interaction between adsorbates and surface. H2O and SO2can adsorb on surface of Cu atoms chemically via molecule form at the coverage of 0.25 ML, while H2O dissociated into OH adsorbed on surface and H bonded with SO2which keeps away from surface at the coverage of 0.5 ML.