COMPARISON OF JETTING-RELATED MICROSTRUCTURES ASSOCIATED WITH HYPERVELOCITY IMPACT CRATER FORMATION IN COPPER TARGETS AND COPPER SHAPED CHARGES

Shaped charge jet and slug formation is characterized prominently by d ynamic recrystallization which may occur in deformation-recrystallizat ion cycles, providing a mechanism for extreme plastic flow in jetting. There was no evidence for melting or melt-related phenomena. Hypervel ocity impact crater development is also dominated by dynamic recrystal lization in a narrow flow zone where target material is jetted into th e crater rim. The crater rim can particulate by velocity gradients alo ng the jetting jet. Like the shaped charge, there was no significant m elt phenomenon associated with the cratering process, and extreme plas tic, high-strain-rate flow occurs in the solid state. Microbands are c reated in a zone removed from the crater wall in copper targets in res ponse to hypervelocity impact which, like deformation twins; are coinc ident with the trace of primary {111} planes. Their density and extent increase with both impact velocity and grain size. Neither microbands nor deformation twins are observed in recovered shaped charge slug an d jet fragments.