Molecular Dynamics Study of the Evolution of Rotational Atomic Displacements in a Crystal Subjected to Shear Deformation

Resumo

The paper analyzes the redistribution of atomic displacements in an initially defect-free copper crystallite after shear deformation with emphasis on the evolution of dynamic structures formed by self-consistent collective atomic rotations. The analysis is based on an original technique which allows one to identify vortex motion in a vector variable space with a discrete step. The results of research show that the direction of consistent atomic motion in vortex structures varies with time and from vortex to vortex. Such spatial alternation of rotations in the material provides its continuity along the boundaries of vortex structures, and their time-variant direction ensures stress and strain transfer from the bulk of the loaded crystal to its peripheral free boundaries. When the strain goes above its critical value, such redistribution can lead to the formation of structural defects. Thus, the vortex structures formed by elastic atomic displacements can be considered as dynamic defects because they provide a way for internal relaxation in the loaded material.