CHARACTERIZATION OF OXIDATION PRODUCTS ON A ZrFe_2-TYPE LAVES INTERMETALLIC EXPOSED TO 200 deg C STEAM

摘要

The release of radioactive elements from the stainless steel-15 wt percent zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe_2-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe_2-type intermetallic sample exposed to 200 deg C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron- oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.