Oxygen embrittlement of Zircaloy-2 on long-term exposure to alkaline earth and rare earth oxides

The purpose of this paper is to present some results of slow strain rate tensile tests in Zircaloy-2 specimens after long-term exposure to SrO, BaO, CeO2, La2O3, Gd2O3 and Y2O3. The degree of embrittlement was determined by comparing the results of annealing in the oxides with those on identical specimens annealed in high-purity argon, in terms of the fracture morphology and of variation of the tensile properties with the annealing parameters. Even at the low annealing temperature of 623 K the specimens were severely embrittled, irrespective of the oxide environment, although annealing times longer than 1000 to 1500 h were needed for embrittlement to occur. The specimens broke with a reduction of area of less than 5%, as compared with over 75% for the samples annealed in the argon environment. The results are given and discussed. (author)