A model is described which makes it possible to calculate the parameters of Hall-Petch relation (the value of grain boundary hardening coefficient K, and the macro-elastic limit sо for nanoand microcrystalline (NMC) metals produced by severe plastic deformation (SPD). The basis for the model is an assumption that the flow stress value in NMC metals has a contribution (alongside with the usual ones from lattice dislocations, impurity atoms, etc.) associated with stresses produced by grain boundary defects arising at SPD. Expressions have been obtained to calculate Hall-Petch relation parameters as dependent on the value and rate of preliminary deformation. Good agreement has been shown between theoretical calculations and experimental data.

The results are described of the study of grain boundary diffusion acceleration phenomenon during the annealing of nanoand microcrystalline (NMC) materials obtained by severe plastic deformation. It is shown to that the coefficient of grain boundary diffusion at recrystallization of NMC materials depends on the lattice dislocation density, grain boundary migration character and rate, and on the predeformation temperature.

A model is described which makes it possible to calculate the value of metal grain refinement limit (GRL) at severe plastic deformation (SPD). Relations have been obtained which describe GRL value dependence on SPD rate and temperature. Good agreement between theoretical calculations and experimental data is shown.