Study of mechanism of oxidation resistance enhancement induced by preformed oxide on zirconium alloys

Abstract The mechanism of oxidation resistance enhancement induced by preformed oxides formed on zirconium alloys was studied. Several tests revealed that preformed oxides formed on Zr-1Nb-1Sn-0.1Fe, Zr-1.1Nb-0.05Cu, and pure-Zr enhanced the oxidation resistance during subsequent oxidation. In addition, the preformed oxides enhanced the oxidation resistance only when they were cooled. Based on the experimental results of present and previous studies, several hypotheses that have been proposed to demonstrate the mechanism of the oxidation resistance enhancement were evaluated. It appears that the monoclinic phase and twin boundaries in the preformed oxide have significant effects on the oxidation resistance enhancement.