On the surface energy of the Cantor alloy and its relation with surface composition

The relatively novel family of materials known as high entropy alloys, popular for exceptional mechanical properties, is currently gaining increasing attention also for remarkable surface properties. Nevertheless, due to the intrinsic difficulties that these materials pose to first-principle modelling, there is a lack of knowledge and understanding of the basics principles that govern their surface energetics. In this work the surface energy of the Cantor alloy was systematically investigated by means of density functional theory within a supercell approach that allows to tackle the effects of local atomic distributions. When properly accounting for the effective simulation slab stoichiometry the Cantor alloy surface energy displays an average value of 1.77 J/m2, ranging between 1.65 J/m2 and 1.95 J/m2. Such values for the Cantor alloy's surface energy are well below those of its constituents also taking into account their variability, supporting the use of this material as anticorrosion coating. Finally, by well assessing a slab total energy decomposition, required to account for the overall slab stoichiometry, an expression is derived which allows to infer the HEA surface energy, for any bulk configuration and surface termination, avoiding slab calculations.