Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 24: Quasicrystals

MM 24.2: Talk

Wednesday, March 29, 2006, 14:15–14:30, IFW D

Molecular dynamics simulation of diffusion processes in decagonal quasicrystals — •Stephen Hocker, Franz Gähler, and Peter Brommer — Universität Stuttgart, Institut für Theoretische und Angewandte Physik, 70550 Stuttgart

Diffusion in decagonal Al-Ni-Co and Al-Cu-Co quasicrystals is investigated by molecular dynamics simulations using newly developed EAM potentials. The potentials are determined with the force matching method: For a selection of small reference configurations, the cohesion energies, stresses, and forces on individual atoms are calculated by ab-inito methods, and the parametrized potentials are adjusted to optimally reproduce these data. One difficulty with these aluminium-rich ternary alloys is that short distances between transition metals are rare in realistic reference structures, so that there is not enough data to determine the short-range part of the transition metal potential accurately. The diffusion properties, however, depend sensitively also on these parts of the potential. Nevertheless, for a number of important diffusion processes the energy barriers determined by molecular statics simulations agree well with the activation enthalpies determined by ab-initio simulations and experimental data.