Dislocation and shear strength of model quasiperiodic lattice

To understand the intrinsic resistance for the dislocation glide in quasicrystals, the glide deformation process in a simple Fibonacci quasiperiodic lattice, consisting of L and S lattice spacings, has been simulated. The Γ-surface of the model fluctuates quasiperiodically and the minima corresponding to the Fibonacci-numbers decrease inversely proportional to the displacement. The Burgers vectors of dislocations, which correspond to neighboring distances of the Γ-surface minima, are almost equal to the lattice spacings. The stress necessary for dislocation glide consists of two components: the phason-defect formation stress and the Peierls stress. Glide of a group of dislocations of a Fibonacci number, associated with one another bounding phason faults, reduces drastically the former stress component and the remaining glide resistance mainly due to the Peierls potential is about 0.015G (G: the shear modulus).