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MM: Fachverband Metall- und Materialphysik
MM 39: Computational Materials Modelling - Alloys I
MM 39.3: Vortrag
Mittwoch, 18. März 2020, 16:15–16:30, BAR 205
Investigating anharmonicity in BCCs: from unaries to HEAs — •Prashanth Srinivasan1, Blazej Grabowski2, Alexander Shapeev3, Jörg Neugebauer4, and Fritz Körmann1,4 — 1TU Delft — 2University of Stuttgart — 3Skolkovo Institute of Science and Technology — 4MPIE Dusseldorf
Anharmonicity is a major contributor to the vibrational free energy of metals, especially at high temperatures. It has been shown for an extensive set of FCC unaries that the anharmonic Gibbs energy contribution is positive and increases with temperature [Glensk et al., 2015]. Unlike in FCC metals, empirical works [Wallace, 2002] suggest some BCC metals to have negative anharmonic contributions to the total free energy. Computational first-principles studies beyond quasiharmonicity are, however, scarce owing to the expensiveness of such calculations. Recent advances combining efficient thermodynamic sampling schemes and machine-learnt moment tensor potential [Grabowski et al., 2019] allow for an efficient yet numerically accurate vibrational free energies determination including anharmonicity. Using this, anharmonic free energies for a set of BCC metals from unaries up to five-component multicomponent alloys are calculated and discussed. As for the unaries, the anharmonicities of different sets of alloys can show both positive as well as negative anharmonic contributions de- pending on alloy composition.