Microstructural characteristics and different effects of 800-1200 degrees preformed oxides on high-temperature steam oxidation of a zirconium alloy cladding

摘要

Zr-1Nb-lSn-0.lFe nuclear fuel cladding tube was pre-oxidised at five different temperatures (803, 908, 1012,1112, and 1200 degrees), and subsequent oxidation tests were performed at 1012 degrees . All the pre-oxidised specimens showed a little or no breakaway oxidation after the subsequent oxidation at 1012 degrees for 5130 s, but the non-pre-oxidised specimen showed a severe breakaway oxidation after the subsequent oxidation at 1012 degrees for 5130 s. In addition, comparing the weight gains and oxide thicknesses of the pre-oxidised specimens with those of the non-pre-oxidised specimens, all the preformed oxides were effective in enhancing the oxidation resistance, and the preformed oxide formed at higher temperature was more effective. The preformed oxides were examined using electron probe microanalyser and transmission electron microscopy, which showed that the fraction of Zr-Sn type precipitates increased with increasing the pre-oxidation temperature. This phase change of the precipitates may cause the preformed oxide formed at higher temperature to exhibit better oxidation resistance enhancement. (c) 2018 Elsevier B.V. All rights reserved.