Mesoscopic Structural States in Plastically Deformed Nanostructured Metal Materials

Abstract

The paper presents experimental data which substantiate the fundamental role of mesoscopic states in plastic deformation as applied to nanostructured metal materials. Such mesoscopic states in a deformed nanostructured material arise at the interstices of lattice curvature zones due to the loss of its translation invariance, abnormally high concentration of nonequilibrium vacancies, and permanent changes in its electronic subsystem. The main mode of plastic deformation in nanostructured materials is noncrystallographic motion of point defects via plastic distortion. There can be also dynamic rotations, structural phase transitions, and formation of nonequilibrium phases absent in phase diagrams. If nonequilibrium vacancies coalesce, nanostructured materials display low plasticity; otherwise, they become superplastic.