High-temperature corrosion of Zr–Nb alloy for nuclear structural materials

Zr–Nb alloy is successfully used as structural materials in nuclear reactors. However, its widespread application is restricted by corrosion due to complex in-pile environments. This work reviews the corrosion behavior and mechanism of Zr–Nb alloy in different simulated nuclear conditions. Nb can exist in the form of Nb²⁺, Nb³⁺ and Nb⁵⁺ in the oxide layer, these oxidized states exert different effects on the space charge distribution of oxides, so affecting oxidation kinetics. Corrosion morphologies of Zr–Nb and elemental compositions of the surface layer in high-temperature water and steam depend on the behavior of β-Nb second phase particles. The difference is obvious under the combined influence of irradiation and material processing process. Optimizing Nb concentration, doping elements, regulating manufacturing parameters and preparing protective coatings are feasible methods to improve the corrosion resistance of Zr–Nb alloy.