Dislocation Glide Resistance in a Model Quasicrystalline Lattice
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Dislocation Glide Resistance in a Model Quasicrystalline Lattice R. Tamura, S. Takeuchi and K. Edagawa1 Department of Materials Science and Technology, Science University of Tokyo, Noda, Chiba 278-8510, Japan 1 Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904, Japan ABSTRACT The glide resistance of edge dislocations gliding along a two-dimensional quasiperiodic lattice (Burkov II model of the decagonal quasicrystal) has been calculated. The glide resistance consists of τ phason and τ Peierls components and the τ Peierls component depends strongly on the orientation of the dislocation. For the orientation of large τ Peierls component, the τ phason component is about half of the τ Peierls component for individual dislocation glide but becomes negligibly small for glide of a pair of dislocations. The largest τ Peierls component is about 0.1G (G: the shear modulus).
INTRODUCTION A quasicrystalline lattice is described by projecting lattice points in a domain of the projection space (perpendicular space) in a high dimensional lattice onto the three dimensional real space (a partial space of the high dimensional lattice). Thus, the Burgers vector of a perfect dislocation in the quasicrystalline lattice consists of the two components: the real space or the parallel space component, b|| , and the perpendicular space component, b⊥ [1]. The b|| component yields a phonon strain field around the dislocation in the same manner as around a dislocation in a crystal, whereas the b⊥ component yields a phason strain field which is not present at a dislocation in a crystal. For the phason field to relax, short range atomic diffusion is necessary, and hence for a perfect dislocation in a quasicrystal to glide without leaving an unrelaxed phason defect field behind, a high enough temperature is needed. Thus, at low temperatures the production of the phason strain field retards the dislocation glide. The other type of resistance for the glide of dislocations in quasicrystals is due to a self-energy variation of the dislocation in the quasiperiodic lattice; this self-energy variation is known as the Peierls potential for crystal dislocations, and we use the same terminology for quasicrystal dislocations. The important role of the Peierls potential in the dislocation glide in quasicrystals is manifested itself in the quite straight nature of dislocations, oriented in a definite crystallographic direction, introduced by plastic deformation in quasicrystals [2 - 4]. In order to clarify the characteristics of the Peierls potential in the quasiperiodic lattice, we have computed the behavior of dislocations in a simple one-dimensional quasiperiodic lattice in a previous paper [5]. In the present paper, we have extended the simulation to a more realistic, two-dimensional quasicrystalline lattice.
K6.4.1
TWODIMENTIONAL MODEL The atomic arrangement of the glide plane in quasicrystals is generally of two-dimensionally quasiperiodic structure, and hence the previous one-dimensional model is not real
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