Berlin 2018 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 68: Transport (Diffusion, conductivity, heat)
MM 68.3: Vortrag
Donnerstag, 15. März 2018, 18:00–18:15, TC 010
Effect of stoichiometry on self-diffusion in triple-defect binary intermetallics: Semi Grand Canonical and Kinetic Monte Carlo simulations. — •Rafal Kozubski1, Jan Betlej1, Piotr Sowa1, Graeme Murch2, and Irina Belova2 — 1M. Smoluchowski Institute of Physics, Jagiellonian University in Krakow, Lojasiewicza 11, 30-348 Krakow, Poland — 2Centre for Mass and Thermal Transport in Engineering Materials, School of Engineering, The University of Newcastle, Callaghan, Australia
Vacancy-mediated self-diffusion and chemical short- and long-range ordering in triple-defect binary intermetallics was modelled with Ising nn and nnn pair interactions and simulated in atomistic scale. The Kinetic Monte Carlo (KMC) algorithm was implemented with local-configuration-dependent migration barriers and temperature-dependent equilibrium vacancy concentration determined by means of Semi Grand Canonical Monte Carlo (SGCMC) simulations. The resulting concentration dependence of the component tracer diffusivities in a triple-defect B2-ordering A-B system mimicking Ni-Al was in a very good agreement with the experimental results obtained for that system. In particular, inversion of the relationship between the Ni and Al-diffusivities in Al-rich Ni-Al systems deduced from the features of interdiffusion in Ni-Al was perfectly reproduced by direct self-diffusion simulations. The origin of the phenomenon is elucidated in terms of an increase of the nnn Al jump frequency resulting from specific atomic and vacancy configurations originating from the triple-defect character of disordering.