SIMS IMAGE-ANALYSIS OF D2O MIGRATION IN ZRO2 THIN-FILMS

The diffusion of D2O into and through oxide films on Zr-Nb alloys was investigated using secondary ion mass spectrometry (SIMS) image analys is. In preparation for this, the microscopic structures of the oxide w ere studied in relation to the grain structures in the underlying allo y. On alloys containing low concentrations of niobium (1-2.5 wt.%), th e oxide was found to exhibit more localized growth, particularly above grain boundaries in the alloy. Such oxide regions appeared to be cons iderably more porous to D2O ingress. By contrast, the oxide film on th e Zr 20 wt.% Nb alloy was found to be the most resistant to D2O ingres s; no local regions of higher porosity could be found. (C) 1997 John W iley & Sons, Ltd.