Physical foundations of crystal structure refinement under severe plastic deformation

The problem of crystal structure refinement under severe plastic deformation has been examined in the framework of the multiscale approach used in strength physics and nonequilibrium thermodynamics. This approach assumes that fragmentation of a solid in the entire hierarchy of the structural-scale levels (nano-, micro-, meso-and macroscale levels) plays a crucial role in the plastic deformation and fracture of materials. Formation of submicrocrystalline or nanocrystalline structure in solids subjected to severe plastic deformation is associated with fragmentation of the strain-induced band structures in the bending internal stress field. Flowing defect boundaries at the lower scale accomodate fragmentation of any curvature in a highly nonequilibrium material under SPD.