The influence of shock prestraining on the structure/property response of hafnium

Highly-textured, crystal-bar-purity hafnium has been shock prestrained at 4.96 and 11 GPa, below the reported alpha to omega phase transformation of 38 GPa. The specimens were “soft caught” following shock prestraining to facilitate quantification of the substructure and post shock constitutive behavior. The substructure of the shocked materials was investigated using optical and transmission electron microscopy. The preshocked Hf samples were subsequently reloaded quasi-statically in compression. The deformation behavior of the as-annealed hafnium under quasi-static conditions is compared to its response following shock prestraining. The reload response is correlated to differences in the defect density due to shock loading