Investigation of relaxation processes in nanocrystalline cobalt produced by severe plastic deformation

It has been shown that the dependence of the width of X-ray diffraction lines of plastically deformed cobalt on the annealing temperature is described by the exponential function. Characteristic temperature regions corresponding to the processes of recovery and recrystallization have been established. It has been shown that the values of the activation energy of recrystallization determined from the experimental data are comparable with the activation energy of the grain-boundary diffusion in metals. The activation energy for the recovery region is considerably lower than the activation energy of migration of nonequilibrium grain boundaries in nanocrystalline metals. The X-ray diffraction data have been confirmed by the investigations of the microstructure and microhardness.