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Science 12 February 1999:
Vol. 283. no. 5404, pp. 965 - 968
DOI: 10.1126/science.283.5404.965
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Reports

Dislocations Faster than the Speed of Sound

Peter Gumbsch, 1 Huajian Gao 1,2

It is thought that dislocations cannot surpass the sound barrier at the shear wave velocity because the energy spent in radiation has a singularity there. Atomistic simulations show that dislocations can move faster than the speed of sound if they are created as supersonic dislocations at a strong stress concentration and are subjected to high shear stresses. This behavior is important for the understanding of low-temperature deformation processes such as mechanical twinning and may be relevant for the dynamics of tectonic faults. The motion of the dislocations at a speed of <RAD><RCD>2</RCD></RAD> times the shear wave velocity can be understood from a linear elastic analysis, but many of the peculiarities of the supersonic dislocations are dominated by nonlinear effects that require a realistic atomistic description.

1 Max-Planck-Institut für Metallforschung, Seestrasse 92, 70174 Stuttgart, Germany.
2 Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.

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