PLASTIC-DEFORMATION OF AL-RU-CU ICOSAHEDRAL QUASI-CRYSTALS

Polycrystalline specimens of Al68Ru15Cu17icosahedral 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 nm3at high stress and 10 nm3at 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. © 1990 IOP Publishing Ltd.