Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 3: Computational Materials Modelling I
MM 3.2: Vortrag
Montag, 14. März 2011, 11:15–11:30, IFW B
Ab-initio-based prediction of the vacancy concentration in the Ni<50Al50 B2 phase — •Tobias C. Kerscher1, Daniel Lerch2, Gus L. W. Hart3, Quinn O. Snell4, and Stefan Müller1 — 1Technische Universität Hamburg-Harburg, Institut für Keramische Hochleistungswerkstoffe, Denickestr. 15, 21073 Hamburg, Germany — 2Universität Erlangen-Nürnberg, Lehrstuhl für Festkörperphysik 2, Staudtstr. 7, 91058 Erlangen, Germany — 3Brigham Young University, Department of Physics and Astronomy, Provo UT 84602, USA — 4Brigham Young University, Computer Science Department, Provo UT 84602, USA
The B2 phase of Ni–Al gains its technical importance from the high melting point (1638 ∘C).
Off its ideal 50-50 stoichiometry, this B2 phase is stabilised by the formation of vacancies on the Ni sublattice.
We use our code UNCLE [1] to construct an ab-initio-based cluster-expansion Hamiltonian for this ternary (Ni, Al, vacancy) system.
Thermodynamic Monte Carlo simulations in the (quasi)grand-canonical ensemble are applied to account for configurational entropy and to predict the equilibrium concentration of the vacancies as a function of temperature.
Since point defect concentrations are expected to be in the order of ppm, the correspondingly large Monte Carlo cells are addressed with the help of a recently demonstrated parallel Monte Carlo implementation in UNCLE.
Supported by Deutsche Forschungsgemeinschaft.
[1] D. Lerch et al., Modelling Simul. Mater. Sci. Eng. 17 (2009), 055003.