Study by deflection of the oxygen pressure influence on the phase transformation in alumina thin films formed by oxidation of Fe3Al

The influence of oxygen pressure on the stability of transition aluminas formed by the oxidation of an Fe3Al intermetallic alloy was studied by means of deflection tests, a technique based on the curvature of an asymmetrical sample consisting of a thin and elongated metallic substrate covered on one face by a protective oxide film. Three different atmospheres were chosen: air, argon and Ar–H2–H2O mixture in order to obtain three different oxygen pressures and different water vapour contents. The deflection results were analysed on the basis of knowledge obtained from kinetics and TEM and SEM microstructural observations.