The early stages of room temperature oxidation of the amorphous alloys Fe 70Cr 15B 15 and Fe 85B 15

Abstract

Oxidation at room temperature of the surfaces of the amorphous alloys Fe 70Cr 15B 15 and Fe 85B 15 has been studied by XPS and AES up to exposures of 10 L. It was found that the presence of Cr promoted the initial reactivity towards oxygen by some 2 orders of magnitude compared to Fe 85B 15. Cr was enhanced rapidly in the surface region of Fe 70Cr 15B 15, while Fe was depleted; conversely, on Fe 85B 15 Fe was enhanced in the early stages of oxidation. On both surfaces the thicknesses of the oxide layers were about 2 nm, comparable with the native oxide film thickness. The binding energy observations were consistent with all species being present in the trivalent state in the oxide films.