The variation of dislocation density as a function of the stacking fault energy in shock-deformed FCC materials

The variation of dislocation density with stacking fault energy (SFE) was measured in shock-deformed Cu and Cu–Al alloys. A differential scanning calorimeter (DSC) was used to measure the stored energy, from which the dislocation density was estimated. The energy released during recrystallization in the DSC experiments was attributed primarily to the annihilation of dislocations with the energy contribution from recovery, deformation twins and point-defects estimated to be relatively small. The dislocation density in the 10 GPa shock-deformed materials first increased and then decreased with increasing Al content (decreasing SFE) while the dislocation density in the 35 GPa shock-deformed materials initially decreased and then remained constant with increasing Al content. This variation in dislocation density in the shock-deformed materials is attributed to the nature of shock-deformation, the influence of stacking fault energy on the dislocation storage mechanisms, and the propensity for deformation twinning.