HYDROGEN TRAPS IN THE OXIDE-ALLOY INTERFACE REGION OF ZR-NB ALLOYS

In this study the H-1(N-15,alpha gamma)C-12 nuclear reaction has been used to measure hydrogen profiles of anodically oxidized Zr-Nb specime ns containing various amounts of niobium. The profiles have been corre lated with oxygen profiles, obtained using a Scanning Auger Microprobe (SAM), and with X-ray diffraction patterns. In addition, unoxidized Z r-2.5Nb (Zr-2.5 wt.% Nb) samples were implanted with oxygen and hydrog en to study the interaction between these two species when dissolved i n the alloy. All the anodically oxidized specimens, except the pure Zr and the single-phase beta-Zr (Zr-20Nb) samples, displayed hydrogen pe aks beneath the oxide layer. These results, in conjunction with the re sults from the implanted specimens, indicate that the hydrogen moves u nder the influence of a stress gradient to the sub-oxide region, where the metal lattice has been expanded due to superficial oxide growth. The results show that dissolved oxygen sites in Zr-2.5Nb alloy do not trap hydrogen.