Hydrogen and oxygen diffusion in zircaloy
Zirconium alloy is used in the nuclear industry as fuel cladding. In case of a loss-of-coolant accident, an oxide layer forms at the Zircaloy surface, and hydrogen and oxygen can diffuse in the metallic part of the cladding, affecting its mechanical properties. It's of primary interest to characterize H and O distribution in the αZr and prior-β phases of zirconium analyses were performed in a zirconium sample first pre-hydrided up to a hydrogen content of 300 wppm and then oxidized at 1000°C in steam to introduce 0.5 wt% of oxygen. SIMS scanning ion images (H-, O- and Red-Green overlay of H- and O- ) highlight the hydrogen segregation into the prior-β phase and the hydrogen depletion of the αZr(O) phase of zirconium. Conversely, αZr(O) phase is enriched in oxygen while the prior-β phase is depleted. Field of view: 300 x 300 µm2. Lateral resolution: ~1 µm.
Recorded on IMS 7f-Auto at CAMECA Application Lab, Gennevilliers, France. Image courtesy of S. Guilbert and D. Suhard, IRSN (France).