Zr-Sn-Nb alloy, widely used as fuel cladding in light water reactors, exhibits sub-parabolic oxidation kinetics distinct from the parabolic behavior of Nb-solute-strengthened Zr-Nb alloys. This difference arises because abundant (Nb,Fe)-rich second-phase particles in Zr-Sn-Nb alloy drastically reduce Nb solid solubility, invalidating the charge-neutrality. Here, we retain the space charge density and numerically solve the built-in electric field evolution without invoking charge neutrality. The electrochemical model for the corrosion of zirconium alloys accurately reproduces Zr-Sn-Nb alloy’s oxidation kinetics at 360℃, yielding a power-law exponent of ~0.41 and a mean absolute percentage error of 4.86%. This work demonstrates that explicitly solving the space charge effect numerically is essential for predicting corrosion behavior of the zirconium alloy where solute compensation is limited.
Zhao et al. (Tue,) studied this question.