Molecular Dynamics Simulations of Crack Propagation in Quasicrystals

Crack propagation is studied in a two-dimensional binary model-quasicrystal by molecular dynamics simulations. Three regimes of motion can be discerned: An intermittent regime with stop and go, a regime of steady motion and an unstable regime with branching. In the rst two regimes the crack tip is emitting disloca-tions, which are followed by a phason wall. Along this wall the material is opening. This is a new fracture mechanism, speciic for quasicrystals. In the third regime the crack is emitting virtual dislocations.