A study was made of the nucleation mechanism of the defects which were responsible for plastic flow in a <100> face-centered cubic perfect single crystal when submitted to a shock wave. In the large-scale non-equilibrium molecular dynamics simulation, small dislocation loops were created from thermal fluctuations just behind the shock front; within a narrow region which was a few lattice parameters in width. Their critical size was determined. The activation energy, for the formation of an edge dipole under high pressures, was estimated within the Peierls framework. The elastic constants and the generalized stacking-fault energy were calculated from the interatomic potential. This model permitted the qualitative consideration of the effect of material parameters, such as intrinsic and unstable stacking faults, versus elastic-energy release.

Dislocation Nucleation Induced by a Shock Wave in a Perfect Crystal - Molecular Dynamics Simulations and Elastic Calculations. D.Tanguy, M.Mareschal, P.S.Lomdahl, T.C.Germann, B.L.Holian, R.Ravelo: Physical Review B, 2003, 68[14], 144111 (10pp)