The Microtopography of Oxide Films on Niobium

Abstract

An electron microscopic study of the oxide films formed on niobium permits the apparently anomalous oxidation rate behavior of niobium to be explained in terms of the formation of small, blister‐like cracks in the oxide film. An oxidation model, based on the idea that an oxidation process which is maintained by interstitial‐anion or anion‐vacancy diffusion leads to the generation of stresses in the oxide film, is proposed to account for these results. The observation of similar blister‐like cracks in oxide films on tantalum is also reported.