Regensburg 2013 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 15: Poster Session
MM 15.40: Poster
Monday, March 11, 2013, 18:00–20:00, Poster E
DFT calculation of cleavage energies and γ-surfaces in Mo2BC hard coatings — •Tobias Klöffel1, Sandra Korte2, and Bernd Meyer1 — 1Interdisziplinäres Zentrum für Molekulare Materialien und Computer-Chemie-Centrum, Universität Erlangen-Nürnberg — 2Lehrstuhl für Allgemeine Werkstoffeigenschaften, Universität Erlangen-Nürnberg
The unusual combination of high stiffness and moderate ductility makes Mo2BC a very interesting material for application as hard protective coating of cutting tools. In order to obtain more detailed insights into the properties of dislocations and plastic deformation in Mo2BC we have calculated the γ-surfaces for several crystallographic crystal cuts using density functional theory. For many simple fcc and bcc metals a detailed atomistic understanding of dislocation properties has been gained on the basis of Peierls-Nabarro models and calculated γ-surfaces. However, such an approach has not been attempted yet for more complex compounds such as Mo2BC. Here, the first results on the shape and properties of the γ-surfaces will be discussed. It will be shown that it is not possible to conclude from the decohesion energy which crystallographic plane will be the active plane for plastic deformation. Finally, the results for the critical Peierls stress and the preferred shear planes will be compared to experimental observations in mechanical tests on micrometer-sized Mo2BC pillars.