Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 32: Metal Substrates I

O 32.6: Talk

Tuesday, March 12, 2013, 11:45–12:00, H42

Fe3Al surfaces in dry and humid oxygen atmosphere — •afshin izanlou, mira todorova, martin Friák, and jörg neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany

The elastic and corrosion properties of iron-aluminides make them interesting candidates for high temperature applications, but the degradation of these properties at room temperature and in the presence of hydrogen hinder their utilisation. Aiming to understand the mechanisms and interactions, which have such negative impact on the properties of these materials, we study the low-index surfaces of Fe3Al in dry and humid oxygen environment, combining density-functional theory with thermodynamic considerations. We find mixed terminated surfaces, i.e. containing both Fe and Al, to be most stable and a marked preference for oxygen adsorption in an aluminium rich environment. This result correlates nicely with the observation that Al2O3 is the thermodynamically stable oxide, when these surfaces come into contact with oxygen. Water, on the other hand, favours adsorption on Fe, on which it adsorbs with the oxygen end. Consequences for the corrosion behaviour and protection of these surfaces will be discussed.