The effects of Ce on the corrosion resistance of Cr13 martensitic stainless steel: experiments and first-principles calculations

Through corrosion weight loss experiments, electrochemical testing, and first-principles calculations, the impacts of Ce on the corrosion resistance of Cr13 martensitic stainless steel and the underlying mechanisms were examined. The corrosion rate of Cr13 martensitic stainless steel exhibited a notable reduction during salt spray corrosion when Ce was present. The electrochemical experiments demonstrate that the self-corrosion current density of the Cr13 steel diminishes from 1.3767 µA · cm −2 to 0.6688 µA · cm −2 after the addition of Ce, and the corrosion potential positively shifts from −373 mV to −370 mV. First-principles calculations indicate that Ce lowers the total density of states (TDOS, the total number of electronic states in the unit energy interval) at and near the Fermi energy level (the highest energy level occupied by an electron at absolute zero) of the Fe-Cr system, which results in a reduction in the transfer of electrons in the Fermi energy level and valence electrons near it between the anode and cathode during corrosion. Furthermore, the high charge density accumulation between Ce and neighboring Fe atoms gives rise to the formation of a covalent bond with high bond energy. Consequently, Ce improves the resistance of Cr13 martensitic stainless steel to corrosion by changing the adjacent Fe atoms’ electronic structure.