Nanostructure formation in copper subjected to high pressure torsion

The obtained results of the microstructure evolution in pure Cu during the severe plastic deformation process indicate a non-monotonous character of the evolution of the structure. The formation of cellular type microstructure with a very high density of the lattice dislocations and the considerable hardening of the material are characteristic features of the first stage of SPD. In the second stage dynamic recovery processes resulted in the transition to the subgrain structure followed by the decrease of the microhardness. The third stage is characterized by the fort-nation of equiaxed nanostructure with high-angle grain boundaries and consider-able crystal lattice elastic microdistortions, which improve the strength characteristics of pure Cu.