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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 15: Crystal Structure Defects / Real Structure / Microstructure

KFM 15.10: Vortrag

Donnerstag, 20. März 2025, 12:30–12:45, H9

Landau Theory for Quasicrystals at the Mesoscale — •Marcello De Donno¹, Luiza Angheluta², Ken R. Elder³, and Marco Salvalaglio^1,4 — ¹Institute of Scientific Computing, TU Dresden, 01062 Dresden, Germany — ²Njord Centre, Department of Physics, University of Oslo, 0371 Oslo, Norway — ³Department of Physics, Oakland University, Rochester, Michigan 48309, USA — ⁴Dresden Center for Computational Materials Science (DCMS), TU Dresden, 01062 Dresden, Germany

Quasicrystals challenge traditional concepts of crystallinity by exhibiting ordered yet aperiodic atomic structures. Their peculiar atomic arrangements give rise to exceptional physical properties, including high hardness, low friction, and remarkable wear resistance, making them worth exploring for high-performance engineering applications. Additionally, their slow dislocation creep leads to high-temperature strength and stability in plastic regimes. We present a mesoscale field theory that unifies the modeling of growth, elasticity, and dislocations in quasicrystals. Using the amplitude formulation of the density-wave representation, our approach models the dynamics of quasicrystals through a free energy functional for complex amplitudes, with non-conserved dissipative dynamics describing their evolution. By specifying only the lattice structure in reciprocal space, our theory self-consistently captures elasticity-including phononic and phasonic deformations-along with defect nucleation and motion. Predictions include the kinematics of dislocations and the formation of semi-coherent interfaces, offering new insights into the mechanics of quasicrystals.

Keywords: Landau-Ginzburg theory; Quasicrystal; Phase-field crystal; Crystal plasticity; Dislocation dynamics