SUBSTRUCTURAL CHANGES AND DISLOCATION GENERATION BEHAVIOR AS A FUNCTION OF PULSE DURATION IN Mo-33Re SHOCKED AT LOW TEMPERATURE.

The changes in substructure and hardening response as a function of shock pulse duration for shocking at 155 K at a nominal pressure of 20 GPa have been studied. In particular, changes in the shock-induced dislocation density as well as the number and nature of deformation twins has been examined. Compared with shocking at 293 K, the rates of generation of dislocations and twins are lower at short durations at 155 K. Although the saturation level and twin thickness do not change with temperature, the saturation dislocation density is greater at 155 K. The results are supportive of the concept of a limiting dislocation generation rate, with the generation involving both fixed sources and multiplication.