Lattice curvature evolution in metal materials on meso- and nanostructural scales of plastic deformation

Abstract

The paper generalizes results of electron microscopy studies of structural states with high lattice curvature which arise in a wide class of materials under various conditions of severe plastic deformation: rolling, equal channel angular pressing, mechanical activation in planetary ball mills, and torsion in Bridgman anvils. The states are divided into two types: 1) a substructural state with elastoplastic lattice curvature of tens of degrees per micron due to high density of like-sign excess dislocations; and 2) a state with elastic lattice curvature up to several hundreds of degrees per micron in volumes of several nanometers. Analysis is performed to inquire into the formation of these states, peculiarities of their evolution, and their role in different mechanisms of plastic deformation and formation of nanocrystalline structures.