Instabilities of high speed dislocations

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Title: Instabilities of high speed dislocations
Authors: Verschueren, J
Gurrutxaga-Lerma, B
Balint, D
Sutton, A
Dini, D
Item Type: Journal Article
Abstract: 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.
Issue Date: 2-Oct-2018
Date of Acceptance: 11-Sep-2018
URI: http://hdl.handle.net/10044/1/64679
DOI: https://dx.doi.org/10.1103/PhysRevLett.121.145502
ISSN: 0031-9007
Publisher: American Physical Society
Journal / Book Title: Physical Review Letters
Volume: 121
Copyright Statement: © 2018 The Author(s). Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/N025954/1
EP/L015579/1
Keywords: Science & Technology
Physical Sciences
Physics, Multidisciplinary
Physics
LATTICE-DYNAMICS MODEL
SCREW DISLOCATION
POINT-DEFECTS
SUPERSONIC DISLOCATIONS
MOLECULAR-DYNAMICS
TRANSIENT MOTION
EDGE DISLOCATION
CRYSTAL
TEMPERATURE
MOBILITY
02 Physical Sciences
General Physics
Publication Status: Published
Article Number: 145502
Appears in Collections:Faculty of Engineering
Condensed Matter Theory
Mechanical Engineering
Materials
Physics
Faculty of Natural Sciences



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