The influence of microstructural evolutions on electrochemical corrosion and passive behavior in precipitation-strengthened high-entropy alloys

Effects of microstructural evolutions on electrochemical corrosion properties and passive film characteristics of precipitation-strengthened (Ni2Co2FeCr)92Al4Nb4 high-entropy alloys (HEAs) were investigated in a saline environment. Compared with single-phase FCC alloys, the appearance of nano-sized L12 particles increases the metastable pitting activities and slightly reduces the pitting potential, while the lamellar D019 phase further deteriorates the localized corrosion resistance. The chemical composition and oxide state of passive films are closely related to the different precipitation scenarios. The corrosion morphologies of the single-phase and L12-strengthened alloys are dominated by pitting, whereas the intergranular corrosion (IGC) and intragranular dealloying-like corrosion occur in the D019-strengthened alloy.