The impact of surface scratches on the corrosion behavior of nanocrystalline high entropy alloy coatings: Electrochemical experiments and first-principles study

To prolong the service life of engineering components used in aggressive environments, a TiZrHfMoW refractory high entropy alloy (RHEA) coating was prepared onto a titanium alloy substrate. Various electrochemical analytical techniques were used to evaluate the corrosion resistance of the scratched RHEA coating in a 3.5 wt.% NaCl solution. The electrochemical corrosion tests indicate that the scratched RHEA coating exhibits a higher electrochemical stability and a lower corrosion rate than the bare titanium alloy. The effects of the localized plastic deformation on the corrosion behavior for the RHEA coating was investigated. A slab model for the RHEA surface was proposed for the first-principles calculation to explored the change of the electron work function (EWF) as a function of external stress. The influence of the constituent elements in the RHEA on the mechanical properties and the electron work function was study to uncover the mechanism underlying the high scratch corrosion resistance of the RHEA coating and provide guidance for the composition design of refractory high entropy alloy.