STRUCTURE AND PROPERTIES OF ULTRAFINE-GRAINED MATERIALS PRODUCED BY SEVERE PLASTIC-DEFORMATION

Strain-heat methods of obtaining ultrafine-grained (UFG) metallic mate rials with grain sizes as small as 20 nm and peculiarities of their st ructure are considered. It is shown that intercrystalline boundaries a re the main element of the structure of UFG materials and that they ar e typically in a non-equilibrium state. The formation of a special gra in boundary phase, i.e. a thin near-boundary layer with high dynamic a ctivity of atoms, has been found. This unusual structure leads to the manifestation of promising new elastic, strength, superplastic, dampin g and magnetic properties of UFG materials.