Abstract
The surface properties of oxides grown on a γ-TiAl (2 at.% Nb) have been examined using X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. An oxide formed on the sample during air exposure at room temperature was thermally destabilized in ultrahigh vacuum. The heating largely decomposed the advanced titanium oxidation states to give a dominant +2 valence configuration at 600 °C, while the aluminum oxide was somewhat enhanced for the same treatment. Growth of a post chemisorption oxide for various temperatures and exposure times at or below a pressure of 10 −6 Torr oxygen revealed the progressive development of titanium and aluminum oxide. At a temperature of 600 °C the titanium component was greatly enhanced relative to the aluminum content in the surface region. This separation of titanium from aluminum was clearly visible in SIMS measurements. The development and thermal stability of these oxides is in agreement with the heats of formation and available valence states for the two majority components in the material.
Published Version
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