Numerical simulation of dislocation motion in an icosahedral quasicrystal

In a large number of experiments it has been proven that plastic deformatio n of quasicrystals can occur by a dislocation mechanism. By the use of mole cular dynamics simulations, we have investigated the application of shear s tress to a three-dimensional model quasicrystal in which we had built an ed ge dislocation of the Peierls-Nabarro type. To determine suitable Burgers v ectors we have calculated the gamma surface, i.e. the misfit energy obtaine d by a rigid shift of two sample halves along a glide plane. The sample was an approximant of the Ammann-Kramer-Penrose tiling decorated according to Henley and Elser (Phil. Mag. B 53 (1986) 59). It consisted of 1 504 080 ato ms interacting via Lennard-Jones potentials. We performed simulations in th e microcanonical ensemble at zero temperature. To detect the dislocation li ne we have used several visualization methods. We have plotted only particl es with a potential energy above a threshold leading to pictures of both th e atoms in the dislocation core and in the stacking fault in the wake of th e dislocation. To distinguish among them we have used image processing algo rithms. The displacement field of the configuration has also been computed. We have observed climb and glide motion of the dislocation. The climb moti on is caused mainly by boundary effects due to the sample geometry. The gli de motion shows kinks due to structural elements that act as pinning center s, The width of the kinks is about 20 quasilattice constants. (C) 2000 Else vier Science B.V. All rights reserved.