Diffusion of Oxygen in Zirconium and Its Relation to Oxidation and Corrosion

The diffusion of oxygen in zirconium and dilute zirconium alloys has been studied in the temperature range of 400° to 5857deg;C by observing the rates of dissolution of anodically deposited interference oxide films. The diffusion coefficient of oxygen in zirconium depends on the grain orientation and varies by a factor of two among different orientations. Macroscopically observed average values obey the equation D , cm 2 / sec = 9.4 exp − 51 , 780 ± 220 / RT where the activation energy for the diffusion of oxygen in zirconium is 51.78 kcal/mole. No macroscopic differences were observed in the diffusion coefficients of the various dilute alloys. Oxidation and corrosion rates have been observed to have an orientation dependence similar to that observed in the diffusion study. The mechanism of oxidation and corrosion is discussed in terms of diffusion of oxygen and adherence of oxide films.