1507 MD Simulation of Dislocation Behavior under Shock Compression

MD simulations of dislocation behavior in KCl under shock compression along the [100], [110] and [111] axis directions are carried out to investigate the elastoplastic transition under shock compression. The dislocations moved along to 45 degrees to the compression direction due to the displacement of atomic lines around its dislocation core. This result is consistent with the Von-Mises hypothesis. Under shock compression along the [111] axis direction, simulation results showed that two edge dislocations were generated due to that two extra half-(011) planes were inserted. The minimum stress for dislocation motion under shock compression along the [111] axis direction was much larger than those under shock compression along the [100] and [110] axis directions. It was suggested that the large stress was caused by the existence of two edge dislocations which were generated by two extra half-(011) planes. The result is consistent with the experimental ones that the Hugoniot-elastic limit (HEL) along the [111] axis direction is much larger than those along the [100] and [110] axis directions.