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Growth and mechanical properties of a MoC precipitate at a Mo grain boundary

An ab initio density functional theory study
: Janisch, R.; Elsasser, C.


Physical Review. B 77 (2008), Nr.9, 9 S.
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
Fraunhofer IWM ()

Atomic- scale stages of the growth of an interfacial precipitate film of tetragonal molybdenum carbide at a Sigma 5 ( 310 ) [ 001 ] symmetrical tilt grain boundary in body- centered cubic molybdenum were investigated by means of atomistic supercell calculations on the basis of ab initio density functional theory. The structural development of the precipitate with increasing carbon concentration is analyzed qualitatively and quantitatively. The structurally optimized atomistic model for the fully developed precipitate is compared to experimental high- resolution images from transmission electron microscopy. Characteristic interface energies are calculated to evaluate the influence of the precipitate on the mechanical stability of the material. Finally, an atomic- scale twinning mechanism in the MoC precipitate is proposed.