Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Topical Session: Combinatorial Materials Science II

MM 23.3: Talk

Tuesday, March 12, 2013, 12:30–12:45, H25

Oxygen Incorporation in Cr2AlC Investigated by Combinatorial Thin Film Synthesis and X-Ray Stress Analysis — •Lin Shang, Moritz to Baben, Jens Emmerlich, and Jochen M. Schneider — Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

The oxygen incorporation in Cr2AlC was studied by combinatorial thin film synthesis. Thin films with chemical concentration gradient were deposited by DC magnetron sputtering from elemental targets, and oxygen was intentionally introduced. Ab initio calculation results indicate that oxygen is incorporated interstitially in the Al layer of Cr2AlC, even for carbon-deficient Cr2AlC. Two phase-regions of Cr2AlC and Cr2Al were investigated in order to study oxygen incorporation in carbon-deficient Cr2AlC. X-ray stress analysis data indicate that the a and c lattice parameters increase with increasing oxygen content. These trends are in good agreement with the change in lattice parameters predicted by ab initio calculations and therefore corroborates the notion of interstitial oxygen incorporation in Cr2AlC. A metastable solubility limit for oxygen of 3.5 at% was determined. This is the first report on interstitial oxygen incorporation in MAX phases and may be of relevance to the initial stages of oxidation.