Dislocation and shear strength of model quasiperiodic lattice

To understand the intrinsic resistance for the dislocation glide in quasicr ystals, the glide deformation process in a simple Fibonacci quasiperiodic l attice, consisting of L and S lattice spacings, has been simulated. The Gam ma -surfnce of the model fluctuates quasiperiodically and the minima corres ponding to the Fibonacci-numbers decrease inversely proportional to the dis placement. The Burgers vectors of dislocations, which correspond to neighbo ring distances of the Gamma -surface minima, are almost equal to the lattic e spacings. The stress necessary for dislocation glide consists of two comp onents: 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 an d the remaining glide resistance mainly due to the Peierls potential is abo ut 0.015G (G: the shear modulus). (C) 2001 Elsevier Science B.V. All rights reserved.