Berlin 2015 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 49: Interfaces I: Structure and Segregation
MM 49.3: Vortrag
Donnerstag, 19. März 2015, 10:45–11:00, H 0107
Why calculated energies of grain boundary segregation are unreliable when segregant solubility is low — Pavel Lejček1, •Mojmír Šob2,3,4, Václav Paidar1, and Václav Vitek5 — 1Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic — 2Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic — 3Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic — 4Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic — 5Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA
We demonstrate that density functional theory based calculations of segregation energies at interfaces are often unreliable when the bulk solid solubility of the segregant is lower than that corresponding to one solute atom per computational repeat cell. In this case, the calculated energy of a solute in the bulk cannot be used when evaluating segregation energies. We document this problem by analyzing the measured and calculated grain boundary segregation energies in nickel and bcc iron available in the literature. On the other hand, even when using repeat cells that are not sufficient for reliable evaluation of the segregation energy, the change in the grain boundary cohesion (strengthening/embrittling energy) may be obtained with a reasonable accuracy.