ANALYSIS OF ZIRCONIUM NIOBIUM PRESSURE TUBE SURFACES FOR HYDROGEN USING SECONDARY ION MASS-SPECTROMETRY (SIMS)

Understanding the mechanisms of hydrogen ingress into pressure tubes fabricated from zirconium–2.5% (w/w) niobium alloy requires knowledge of the hydrogen concentration in the surface oxides, of the oxide/metal interface and in the alloy phase beneath the interface. Secondary ion mass spectrometry (SIMS) has attractive capabilities for detecting hydrogen isotopes in such surface films, but its quantitative response and spatial resolution are controversial for hydrogen because of the strong tendency for the element to migrate, owing to thermal and sputtering effects. High sputter rate conditions have been used here, which result in an improved capability to detect hydrogen in ZrNb alloy and ZrO2 down to concentrations of <2 × 1017 atoms cm−3 (<0.1 ppm, w/w). Quantitation of deuterium concentrations has been accomplished by SIMS calibrated using ion implants and, in some cases, verified by nuclear reaction analysis (NRA). Copyright © 1990 John Wiley & Sons Ltd.