In-situ electrochemistry and mechanism investigation of the enhanced corrosion resistance of Zr-Sn-Nb alloy enabled by self-ion implantation

High-temperature aqueous corrosion significantly limits the lifespan of zirconium alloys in high-burnup pressurized water reactors. This study evaluates the effect of self-ion implantation on the corrosion behavior of the N36 alloy. Corrosion tests were performed on N36 alloys implanted with various Zr 2+ doses, followed by in-situ electrochemical tests in 360 o C lithiated/borated water. Results showed that Zr 2+ implantation induced surface hardening and promoted elements segregation and dilution, resulting in a notable reduction in corrosion rates, particularly at higher doses. The influence of Zr 2+ implantation on corrosion was validated by potentiodynamic polarization and electrochemical impedance spectroscopy, and the mechanisms were discussed. The implantation-induced effects synergistically stabilize the protective t-ZrO 2 phase. This promotes the formation of a denser, more protective oxide film, characterized by mitigated porosity in the outer layer and a refined inner columnar structure. Consequently, the densified oxide film acts as a superior barrier, leading to an improvement in corrosion performance.