Corrosion resistance and passive film characteristics of Sc-added Al1.2CoCrFeNi high-entropy alloys in sulfuric acid solution

• Sc addition induces formation of a (Ni, Co)2Sc Laves phase with FCC structure, which is preferentially corroded due to high electrochemical activity. • Sc significantly accelerates corrosion rate in 0.5 mol/L H2SO4, leading to poorer corrosion resistance compared to NaCl solution, with severe intergranular corrosion. • Passive films on Sc-containing alloys incorporate Sc2O3 and exhibit p-n junction electronic characteristics, with defect density increasing from 10^21 to 10^23 cm^-3 as Sc content rises. • The study provides critical insights for designing corrosion-resistant high-entropy alloys for acidic environments, guiding engineering applications.