Potential-dependent Cr/Mo ratio effect on the passivity of Fe-based metallic glass in simulated wet storage environment of spent nuclear fuels

Abstract

The corrosion resistance of Fe-based metallic glasses (MGs) with different Cr/Mo ratios in simulated wet storage environment for spent nuclear fuels were systematically examined. Results reveal that the Cr/Mo ratio exhibits different effects on the corrosion resistance of the Fe-based MGs at different potentials. At low potential, the passive current density decreases gradually with the increment of Cr/Mo ratio. This is related to the enrichment of Cr oxides and the reduction of defects densities in the passive film, which inhibit the diffusion of Cl⁻ and the dissolution of the film. Interestingly, at high potential, as the Cr/Mo ratio increases, the corrosion property of the Fe-based MGs enhances initially and then deteriorates, and Cr₁₀Mo₅ alloy demonstrates the best corrosion resistance. This is because at the appropriate Cr/Mo ratio, the potential can encourage the accumulation of Mo in passive films while also promote film thickening. This process enhances the electronic work function of the passive film, which contributes to the improved corrosion resistance. This research provides a new perspective for the designing corrosion-resistant Fe-based MGs for the wet storage of spent nuclear fuels.