1989 Volume 29 Issue 3 Pages 246-252
Surface oxidation of an Fe–30Mn–9Al alloy has been performed in the temperature range between 295 and 671 K at low oxygen exposures from zero to saturation coverages under ultrahigh vacuum conditions. Chemical composition changes in the thin oxide layers formed during the oxygen uptake have been measured by means of Auger electron spectroscopy and the nature of the initial oxidation by secondary ion mass spectrometry. Preferential enrichment and oxidation of aluminum occurs at room temperature with concurrent depletion of iron from the surface layer. On increasing the temperature without oxygen exposure, enrichment of manganese in the surface layer becomes predominant above about 400 K. Oxygen exposure of the surface results in the formation of oxide layers of which the outermost part is enriched in manganese. It is shown that the manganese oxide formation at high oxygen pressures inhibits the formation of the protective aluminum oxide scale resistant to high temperature oxidation of Fe–Mn–Al alloys.
