Oxidation behavior of β-Nb formed in Zr-1Nb under neutron irradiation in PWR conditions

This work focuses on neutron irradiated Zr-1Nb alloy, using High Resolution Transmission Electron Microscopy (HRTEM) to investigate the oxidation behavior of beta-Nb at different distances from the Oxide /Metal (O/M) interface within the oxide film. Results show that beta-Nb was initially oxidized to T-NbO2 at 0 nm at O/M interface, then into a complex morphology of T-NbO2, M-Nb2O5, and O-Nb2O5 within 600 nm. Finally, it was completely oxidized to M-Nb2O5 within 800 nm. beta-Nb in this study did not exhibit amorphous morphology within observed distances. In addition, Inverse Fast Fourier Transformation (IFFT) and Weak Beam Dark Field (WBDF) techniques are employed to characterize the dislocation density and distribution in the oxide film, results indicate that the distribution of dislocations generated by neutron irradiation in the oxide film is relatively uniform and neutron irradiation is not the primary reason affecting the oxidation behavior of beta-Nb.