Propagating lattice instabilities in shock-loaded metals

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Abstract
The first atomic-scale simulations of shock propagation using accurate many-body atomic interactions have been performed. Shock propagation in copper was modeled with use of the embedded-atom method. Lattice instabilities, consisting of crystallographic twinning boundaries and martensitic regions, were observed to form and propagate behind the shock front for impact velocities as low as 0.01 km/sec. The twinning boundary dislocations cause a loss of shear strength, resulting in a significant reduction in shock-wave velocity, without the accompaniment of permanent crystallographic damage. This new mode of lattice deformation is qualitatively different from the behavior characteristic of pairwise atomic interactions.