Evolution of stress fields and phase content in corroded zirconium cladding materials

In this study, the evolution of stress fields and structural phase composition have been studied using Raman spectroscopy pre- and post-transition in the oxide layer of re-crystallised ZIRLO and recrystallised zircaloy-4 (Zr-4) after corrosion exposure in a static autoclave. The structural phase composition analysis showed that the proportion of the tetragonal zirconia phase on the surface decreased with increasing corrosion time. High compressive stresses were found in the thin oxide, increasing with corrosion time, reaching a maximum in the transition period and decreasing slightly after that. The results show the relationship between the crystallographic phase and the residual stresses developed in the oxide.