DIFFUSION NUCLEATION OF CAVITIES IN GRAIN JUNCTIONS OF SUBMICROCRYSTALLINE MATERIALS

The conditions of diffusional cavity nucleation in submicrocrystalline materials processed by the methods intensive plastic deformation (equal-channel angular pressing, multiaxial forging, high pressure torsion, etc.) are analyzed. To date, question mechanism cavities such remains debatable due to fact that processing is carried out at hydrostatic pressures prevent appearance pores. possibility diffusive nanopores region triple junctions grains containing negative strain-induced wedge disclinations, generating tensile stresses vicinity junctions, comparable magnitude external pressure, shown. Such junction disclinations inevitably occur grain heterogeneity through ensemble polycrystal grains. It shown an important condition for not only presence internal from but also extremely concentration nonequilibrium vacancies characteristic metals, values vacancy concentration, temperatures close solidus. influence strength value and degree supersaturation material nonequilibriumstrain-induced on rate volume critical pore nuclei established order effectively suppress process formation boundary it necessary apply compensates elastic fields disclinations.