Kinetics of dislocation emission in 3D: from the crack toward the free surface

Abstract

The kinetics of dislocations emitted from a crack is studied via molecular dynamics (MD) in a 3D bcc iron crystal. The atomistic results show that edge dislocation segments in the middle of the crystal accelerate at the nearest vicinity of the free crystal surface. The dislocations in MD penetrate the surface layers in transonic or supersonic regimes. The possible sources for such behavior are discussed in the framework of continuum models and using stress calculations on the atomistic level. Acoustic emission patterns arising from the fast dislocation motion in MD are visualized via the local kinetic energies of individual atoms and further modeled as a moving source of the stress waves in the anisotropic continuum.