Effects of Sn on the oxidation and oxide characteristics of Zr alloys in water and a LiOH solution

Abstract

To investigate the Sn effects on the oxidation and oxide characteristics of Zr-xSn (x=02.0wt%) binary alloys, autoclave tests were performed in pure water and LiOH solutions containing 2.2 and 70 ppm Li. Corrosion behavior of the Zr-xSn binary alloys was found to be highly dependent on the Sn content and test environment. Corrosion resistance of the Zr-xSn alloys decreased with increasing Sn content in pure water, but increased with increasing Sn content in the LiOH solution. In pure water, a high Sn content accelerated transformation of the oxide microstructure from a columnar grain to an equiaxed grain and the oxide crystal structure from tetragonal to monoclinic. However, this trend was not maintained in the LiOH solution because Li-penetration into the oxide played a more important role than Sn in the transformation of the oxide properties. It is suggested that high Sn content tends to retard Li-penetration into the oxide in LiOH solution.