Electrochemistry Behavior and Surface Film Characterization of Fe50Mn30Co10Cr10 medium Entropy Alloy in Sulfuric Acid Solution

The Fe50Mn30Co10Cr10 medium entropy alloy (MEA) has been found to yield superior mechanical properties to CoCrFeMnNi Cantor high entropy alloys (HEA) due to transformation induced plasticity (TRIP) effect. However, the corrosion resistance between these two alloys has not been compared. In this study, the corrosion behavior of MEA and HEA was investigated in 0.1M H2SO4 solution at ambient condition. The preliminary results showed that both alloys exhibited the passive behavior with similar passive current density in 0.1M H2SO4 solution; nevertheless, some differences in anodic features and critical anodic current densities were found by comparing their anodic branch of the polarization curve. The SEM surface observation revealed both alloys tended to suffer uniform corrosion and intergranular corrosion in 0.1M H2SO4 solution. The microstructure and composition of passive films formed in 2 h on MEA and HEA at 440 mVSCE in 0.1M H2SO4 solution were also investigated in this study. The high resolution transmission electron microscope (HRTEM) pictures showed that the passive film formed on the MEA was approximately 2-5nm thick with amorphous structure.