Instabilities of High Speed Dislocations.
Phys Rev Lett
American Physical Society (APS)
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Verschueren, J., Gurrutxaga-Lerma, B., Balint, D., Sutton, A., & Dini, D. (2018). Instabilities of High Speed Dislocations.. Phys Rev Lett, 121 (14), 145502. https://doi.org/10.1103/PhysRevLett.121.145502
Despite numerous theoretical models and simulation results, a clear physical picture of dislocations traveling at velocities comparable to the speed of sound in the medium remains elusive. Using two complementary atomistic methods to model uniformly moving screw dislocations, lattice dynamics and molecular dynamics, the existence of mechanical instabilities in the system is shown. These instabilities are found at material-dependent velocities far below the speed of sound. We show that these are the onset of an atomistic kinematic generation mechanism, which ultimately results in an avalanche of further dislocations. This homogeneous nucleation mechanism, observed but never fully explained before, is relevant in moderate and high strain rate phenomena including adiabatic shear banding, dynamic fracture, and shock loading. In principle, these mechanical instabilities do not prevent supersonic motion of dislocations.
External DOI: https://doi.org/10.1103/PhysRevLett.121.145502
This record's URL: https://www.repository.cam.ac.uk/handle/1810/286218
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/