Abstract
The oxidation phenomena of Zr-Te alloy were studied using the tracer technique. Small amounts (0.1∼0.3%) of 127mTe-127Te, whose specific activity was about 5 mc/g, were added to pure reactor grade zirconium sheets by diffusion at 950°C. The alloy specimens thus obtained were oxidized in air or heated in vacuo at 750°C for 30 hrs. Measurements of the activity from the specimen surface with a G.M. counter showed that zirconium oxide formed by the oxidation treatment contained almost the same quantity of tellurium as the zirconium alloy. By separate counting of internal conversion electron from the 127mTe and β-ray from the 127Te using a 13.6 mg/cm2 aluminum absorber, we observed that the surface concentration of tellurium was raised markedly by annealling in vacuo, but not by oxidation in air. It is concluded that tellurium is far less movable in the oxide than in the zirconium alloy, suggesting that tellurium ions are trapped by oxygen-ion vacancies in the zirconium oxide. This trapping action, at the same time, decreases the mobility of the oxygen-ion vacancies. The good oxidation resistance of Zr-Te alloy is explained by this mechanism.
