Dislocation-climb plasticity: Modelling and comparison with the mechanical properties of icosahedral AlPdMn

A model of plasticity controlled by the pure climb motion of dislocations is proposed and compared with the mechanical properties of icosahedral AlPdMn. This model takes into account the chemical stress due to an out-of-equilibrium average concentration of vacancies, and the difficult nucleation of jog-pairs on climbing dislocations. It accounts for several unexplained properties of AlPdMn, namely a high strain-hardening at yield, a steady-state flow stress twice higher than the elastic limit, and two-stage relaxation curves. It also explains values of the stress-strain rate sensitivity larger than expected a priori, and activation energies larger than the self-diffusion one. The model may also be applicable to high-temperature deformation of crystals. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.