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MM: Fachverband Metall- und Materialphysik
MM 41: Computational Materials Modelling VI - Dislocations
MM 41.4: Vortrag
Mittwoch, 2. April 2014, 12:15–12:30, IFW D
Metadislocation core structure in the ε-Al-Pd-Mn phases — Benjamin Frigan and •Hans-Rainer Trebin — Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Germany
In the past we have energy optimized the bulk structures of the ε-phases and the 16 Å decagonal phase of Al-Pd-Mn using density functional theory (DFT) and classical molecular dynamics. All phases consist of columns of pseudo-Mackay icosahedra (PMI) whose projections form tilings of hexagons, pentagons and nonagons in the ε-phases and several other tiles in the decagonal phase.
Most parts of the metadislocation cores in the ε-phases display the same cluster arrangements as in the bulk phases. Nevertheless, in small sections of the cores the usual cluster description fails. Recent microscopy images indicate that the central parts contain 1/τ shorter PMI-PMI next-neighbor distances. The structure of these novel cluster intersections has been resolved with DFT calculations using the smallest possible approximant which contains such interpenetrating PMI clusters.
We present a full structure description of the metadislocation cores F3 and F5. Embedded in bulk structures of ε-phases the cores have been relaxed using a combination of classical molecular dynamics and a Monte Carlo method where the chemical species were randomly flipped.