Modelling the strength of ultrafine-grained and nanocrystalline fcc metals

A model for predicting the steady-state flow stress in ultrafine-grained and nanocrystalline face-centred cubic metals based on irreversible thermodynamics is presented. Grain size, temperature and strain-rate effects are incorporated. Nanoscale effects are accounted for via dislocation propagation and annihilation mechanisms invoking an Orowan-type dislocation glide mechanism, and a vacancy-mediated annihilation mechanism at the interface, respectively. Model predictions show good agreement with experiments for pure Cu and Al