Plastic deformation of Al-Cu-Fe icosahedral quasicrystals

Poly-quasicrystalline specimens of the Al-Cu-Fe system have been pre-strained and further deformed at various temperatures, above and below the brittle-to-ductile transition temperature, under constant strain-rate conditions. The experiments have been specially designed to examine the respective contributions of the thermally reversible and structural dependent parts to the total flow stress. We show that the so-called internal stress, which results from the deformation builtin microstructure, has a rather low value, if any. In addition, the flow stress is found to be fully temperature reversible, if one takes into account previous plastic strains. We suggest that these results can be explained by a weakening of the friction stress, due to the formation of soft slip bands.