Le. Murr et al., COMPARISON OF JETTING-RELATED MICROSTRUCTURES ASSOCIATED WITH HYPERVELOCITY IMPACT CRATER FORMATION IN COPPER TARGETS AND COPPER SHAPED CHARGES, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 222(2), 1997, pp. 118-132
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.