On the Limiting Minimum Size of Grains Formed in Metallic Materials Produced by High-Pressure Torsion

Results are presented concerning the experimental studies of the limiting minimum grain size d (min) in nanostructured metallic materials produced by high-pressure torsion in Bridgman anvils. It is shown that important factors that determine d (min) in the process of severe plastic deformation are the critical stresses for dislocation shear and the mobility of point defects, which control the paths of these defects in stress fields, the characteristic scales of the microvolumes involved into reorientation processes, and therefore the sizes of grains and subgrains of submicroscopic and nanoscopic scales.