The Røcle of hydrogen in the high‐temperature corrosion of zirconium and its alloys. I. The effect of cathodic polarization on corrosion in water at 325°

Binary zirconium alloys and Zircaloy 2 have been corroded in water at 325°c with and without cathodic polarization. In some cases polarization can increase hydrogen uptake or reduce the protective character of the oxide films as assessed by capacity measurements. Alloying elements significantly influence both effects, but comparison of the alloys shows no systematic relation between their hydrogen uptakes and the loss of protective character of their films. Films formed in a previous period of unpolarized corrosion are damaged when polarized at 325° and at room temperature. Possible explanations of the effects of hydrogen and of alloying elements are suggested.