Dislocation multiplication in f.c.c. metals at presence of high shear stress

A new model of shock-induced stress relaxation based on multiplication and motion of partial dislocations bounding the stacking fault is suggested. Shock-generated high shear stress leads to stretching of lateral branches of a bowed out dislocation segment (half-loop) followed by collapse of those branches. The result of the collapse is the forming of the "fresh" partial dislocation loop bounding the stacking fault area and "initial" dislocation half-loop, both being capable of the next multiplication act. After every collapse time interval ΔT the process leads to the doubling of both the dislocation concentration and stacking faults total area. The energy dissipation rate behind the shock front increases exponentially, dW/dt ≈ 2^t/ΔT but it should be limited as soon as the cross-slip of the "fresh" loops will be impended and the loops doubling will be stopped. An explanation of twinning and shear bands formation in shocked material is proposed.