Influence of hydrogen charging on electrochemical behavior and passivation of the FeCoCrNiMo0.1 high entropy alloy

Purpose The purpose of this paper is to investigate the electrochemical behavior and passivation of the FeCoCrNiMo0.1 high entropy alloy (HEA) under the effect of hydrogen. Design/methodology/approach Electron channeling contrast imaging (ECCI) was used for characterizing surface damage. The electrochemical behavior and passive film composition were studied by means of potentiodynamic polarization measurement and X-ray photoelectron spectroscopy (XPS). Findings The results show that hydrogen charging increases localized dislocation density, and with hydrogen charging time elapsing, hydrogen damage is intensified. When hydrogen charging time reaches 360 min, many intergranular cracks emerge. In addition, hydrogen facilitates passive film breakdown and degrades the protective nature by varying the composition. With hydrogen effects, the proportion of OH–, Cr(OH)3 and metallic Mo increases and the proportion of O2–, Cr2O3 and Mo oxides decreases. Consequently, hydrogen increases electrochemical activity. Originality/value The paper aims to provide guidance for the safe service of HEAs and the development of hydrogen-resistant alloys.