Effect of shock compression method on the defect substructure in monocrystalline copper

Abstract

Monocrystalline copper samples with orientations of [001] and [221] were shocked at pressures ranging from 20 GPa to 60 GPa using two techniques: direct drive lasers and explosively driven flyer plates. The pulse duration for these techniques differed substantially: 40 ns for the laser experiments at 0.5 mm into the sample and 1.1 ~1.4 µs for the flyer-plate experiments at 5 mm into the sample. The residual microstructures were dependent on orientation, pressure, and shocking method. The much shorter pulse duration in the laser driven shock yielded microstructures closer to the ones generated at the shock front. For the flyer-plate experiments, the longer pulse duration allows shockgenerated defects to reorganize into lower energy configurations. Calculations show that the post-shock cooling for the laser driven shock is 10 3 ~ 10 4 faster than that for plateimpact shock, propitiating recovery and recrystallization conditions for the latter. At the higher pressure level, extensive recrystallization was observed in the plate-impact samples, while it was absent in the laser driven shock. An effect that is proposed to contribute significantly to the formation of recrystallized regions is the existence of micro-shear-bands, which increase the local temperature beyond the prediction from adiabatic compression.

Deformation Substructures and Their Transitions in Laser Shock–Compressed Copper-Aluminum Alloys

“…The calculations were conducted for an initial pressure of 60 GPa and temperature of 300 K. The specimen lengths are 1 mm for laser shock and 250 mm for plate impact shock. The calculations were carried out according to the method described by Cao et al [2].…”

“…Most of the studies were carried out with plate impact, where the plate was accelerated by gas-gun or explosives [2]. Today, laser shock and isentropic compression experiments are rapidly evolving as effective methods to explore the extreme pressure, strain-rate and temperature regimes inaccessible through other techniques [3][4][5].…”

Dynamic Response and Microstructure Evolution of Oxygen-Free High-Conductivity Copper Liner in Explosively Formed Projectile

“…The release from shock state to initial state is usually assumed to be isentropic. The shock temperature T s can be calculated by [Cao et al, 2005] …”

Surface topography evolution of Ni-based single crystal superalloy under laser shock: Formation of the nano-scale surface reliefs

“…between internal microstructures and mechanical performances [13][14][15][16]. For instance, microstructure characterization of monocrystalline copper subjected to laser-induced shock was investigated, and the results showed the evolution of defect structures.…”

“…For instance, microstructure characterization of monocrystalline copper subjected to laser-induced shock was investigated, and the results showed the evolution of defect structures. However, aspects regarding the surface integrity were not involved in the mentioned studies [14,16]. Alternatively, the surface integrity played an important role in the fatigue tests of workpieces indeed [17,18].…”