Regensburg 2007 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 11: Interfaces III
MM 11.1: Talk
Monday, March 26, 2007, 14:45–15:00, H6
Carbide precipitation at a grain boundary in molybdenum - an ab-initio DFT study — •Rebecca Janisch1 and Christian Elsässer2 — 1Universität Erlangen-Nürnberg, Institut für Werkstoffwissenschaften (WWI), Martensstr. 5, 91058 Erlangen, Germany — 2Fraunhofer-Institut für Werkstoffmechanik, Wöhlerstr. 11, 79108 Freiburg, Germany
Atomic-scale stages of the growth of an interfacial precipitate film of tetragonal molybdenum carbide at a Σ5 (310) [001] symmetrical tilt grain boundary in molybdenum were investigated by means of atomistic supercell calculations on the basis of ab-initio density functional theory (DFT). In this presentation, the structural development of the precipitate with increasing carbon concentration is analysed. The structurally optimised atomistic model for the fully developed precipitate is compared to experimental high-resolution images from transmission electron microscopy, and it allows to clarify some ambiguous features therein. An atomic-scale twinning mechanism in the MoC precipitate is proposed. Finally, the influence of the carbon concentration on the stability of the metal-carbide interface with respect to cleavage is discussed.