Alloy 22 (UNS N60622) was studied in simulated aqueous environments related to the Yucca Mountain repository for its passive and transpassive corrosion behavior. The corrosion potential ennoblement phenomenon was observed on Alloy 22 in multi-ionic solutions. The electrochemical properties and stability of the passive film were investigated by conducting potentiostatic, linear polarization resistance, and AC impedance measurements. Results show no detrimental effect from the corrosion potential ennoblement. The ennoblement increased the resistance to passive dissolution. The polarization in the passive region increased thickness of inner barrier layer of passive film, while the polarization at a transpassive potential formed a less protective porous surface film on Alloy 22.
Keywords: Alloy 22, simulated ground waters, potentiostatic, polarization resistance, AC impedance, passive film, inner barrier layer, porous layer, corrosion potential ennoblement, passive dissolution, transpassive dissolution.