INCORPORATION OF TUNGSTEN SPECIES INTO THE ANODIC FILM ON ZR-2.7 ATOMPERCENT W ALLOY

The present study examines anodic oxidation of a dilute Zr-W alloy for which enrichment of tungsten in the alloy is expected from thermodyna mic considerations. However, no significant enrichment of tungsten, wi th an upper limit determined by the resolution of the analysis of abou t 1 x 10(18) tungsten atom m(-3), is developed during formation of the anodic film. The relative lack of enrichment is attributed to the cry stalline structure and growth mechanism of the film on the Zr-W alloy The film is composed of zirconia, contaminated by tungsten species thr ough its thickness, which develops mainly at the alloy/film interface by inward migration of oxygen ions via short-circuit paths.