A study of the interphase structure at the oxide-metal interface in the corrosion of zirconium-based alloys

The nature of the oxide layer that formed during corrosion of zirconium-based alloys in a pressurized, lithiated water environment at 300oC was determined through scanning electron microscopy study of the oxide-metal interface region as well as X-ray diffraction and electron diffraction analyses. Alloys examined included cold-worked Zr-2.5wt%Nb, heat-treated Zr-2.5 wt%Nb, Excel alloy (Zr-Sn-Mo-Nb), pure zirconium and cold-worked Zircaloy-4(Zr-Sn alloy). The metallographic observations and corrosion kinetics studies show that variations in the oxidation rate among the zirconium-based alloys result from the differences in structure of the interphase layer at the oxide-metal interface. (Author)