Supersonic dislocations

Article By:

Gumbsch, Peter Max-Planck-Institut fur Metallforschung, Stuttgart, Germany.

Last reviewed:2001

DOI:https://doi.org/10.1036/1097-8542.YB011540

The existence of dislocations was postulated almost 100 years ago to explain permanent plastic deformation and nonlinear behavior in materials under large loads. The importance of dislocations for the scientific understanding and development of materials was recognized during the 1930s. Today, it is well known that dislocations are line defects in the crystalline order of materials and act as a vehicle of translation within the material, like a wave in the carpet helps to move it across the floor. Dislocations are the main carriers of plastic deformation in metals or semiconductor crystals, but they are also formed when parts of the Earth's crust move against each other. Dislocation motion governs the forming of almost all engineering parts, ranging from wire drawing to the forming of aircraft bodies. Understanding the dynamics of dislocation motion is therefore the key to the explanation of many different materials processes and phenomena ranging from the deep drawing of metal cans to the brittle or ductile response of materials, and reaches geological dimensions with the description of fault propagation during earthquakes. The recent finding of dislocation motion at supersonic velocities is of outstanding importance in this respect, since it was believed until then that dislocations cannot surmount the barrier at the shear wave velocity.

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