Plastic Deformation of Al-Ru-Cu Icosahedral Quasicrystals

Abstract

Polycrystalline specimens of Al 68 Ru 15 Cu 17 icosahedral quasicrystals are brittle below 1000 K but plastically deformable above 1000 K with the flow stress sensitively depending on the strain-rate. The activation analyses show that the activation volume is less than 1 nm 3 at high stress and 10 nm 3 at low stress. The obtained activation enthalpy is anomalously high, ∼10 eV at low stress, and the pre-exponential factor is unreasonably large, suggesting that the simple Arrhenius rate equation is not appropriate for describing the deformation of quasicrystals. Discussion on the special feature of dislocation motion in quasicrystals is given.