Oxidation behavior and microstructural evolution of Zr-1.0Nb-0.01Cu during high-temperature transients

To study the oxidation behavior and microstructural evolution of Zr-1.0 Nb-0.01Cu claddings during high-temperature transients simulating LOCA scenarios, samples were oxidized to 850, 900, 1000, 1100 and 1200 ℃ at heating rates of 25 and 50 ℃/min. The oxidation data show a similar trend from a parabolic to a cubic rate law. Then, the cross-sectional morphology, phase distribution, orientation, crystal structure and stress distribution were characterized. Monoclinic ZrO2 oxide shows a fiber texture. The suboxide ZrO at the ZrO2/Zr3O interface from presence to absence is a continuous process with increasing temperature. The presence of ZrO could be associated with local stresses.