Impact of intermetallic precipitates on hydrogen distribution in the oxide layers formed on zirconium alloys in a steam atmosphere: a D-2(He-3,p)alpha nuclear analysis study in microbeam mode

摘要

The aim of this study is to try and achieve a better understanding of the role of Zr(Fe,Cr)(2) and Zr-2(Fe,Ni) intermetallic precipitates in the hydrogen uptake mechanisms during aqueous corrosion of zirconium alleys at 400 degrees C. The deuterium distribution in the oxide layers was studied by nuclear analysis using the D-2(He-3,p)alpha reaction in microbeam mode. The oxide thicknesses studied are between 0.7 and 1.4 mu m. Preliminary results show that for oxide layers 0.7 mu m thick, the presence of a zirconium hydride is very often detected under the metal/oxide interface in the vicinity of a precipitate in the oxide. This correlation is not observed for oxide layers 1.4 pm thick. These results are interpreted as an indication of the role of precipitates as hydrogen diffusion short-circuits through the zirconium layer, but only when these precipitates are metallic and still in contact with the metal, i.e., at the very early stages of oxidation. (C) 1998 Elsevier Science S.A. [References: 37]