Identification and Space-Time Evolution of Vortex-Like Motion of Atoms in a Loaded Solid

Resumo

The paper studies the redistribution of internal stresses and atomic displacements in a preloaded copper crystallite using the molecular dynamics method. It is shown that relaxation within the crystallite volume is accompanied by the formation of dynamic structures in which atomic displacements produce a coherent system of vortex lines. In so doing, the displacement of atoms in neighboring vortex structures has the opposite sign of the angular velocities. The evolution of the dynamic vortex structures is analyzed using an original technique for identifying the vortex motion in the space of a vector variable with a discrete step. It is shown that a system of dynamic vortices and antivortices can propagate inside the crystallite, ensuring the transfer of stresses from the bulk of the loaded material to its unloaded periphery in order to preserve continuity. The developed technique has revealed that the lifetime of such defects depends on their size and ranges from fractions to tens of picoseconds. The simulation results correlate well with the experimental electron microscopy data on the estimation of spatial parameters and lattice curvature during strain localization in the region of elastic distortions.