Dislocations and plasticity of quasicrystals

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Abstract
The experimental observations on dislocations in quasicrystals are reviewed with particular emphasis on contrast behaviour in transmission electron microscopy. Quantitative contrast experiments indicate that the phason-strain field of dislocations in icosahedral Al-Cu-Fe is by about an order of magnitude stronger than the phonon-strain field. The data on room-temperature plastic deformation of quasi-crystals are reviewed. Depending on the alloy, Vickers hardness values range from about 400 to 1000. Microcracks are observed under the Vickers indentations. The hardness decreases steeply with increasing temperature. Controlled single-quasicrystal experiments indicated that high-temperature deformation is carried by a dislocation mechanism.