The strength of single crystal copper under uniaxial shock compression at 100 GPa

Abstract

In situ x-ray diffraction has been used to measure the shear strain (and thus strength) of single crystal copper shocked to 100 GPa pressures at strain rates over two orders of magnitude higher than those achieved previously. For shocks in the [001] direction there is a significant associated shear strain, while shocks in the [111] direction give negligible shear strain. We infer, using molecular dynamics simulations and VISAR (standing for 'velocity interferometer system for any reflector') measurements, that the strength of the material increases dramatically (to approximately 1 GPa) for these extreme strain rates.

Nanosecond white-light Laue diffraction measurements of dislocation microstructure in shock-compressed single-crystal copper

“…Indeed, such time-resolved X-ray diffraction (TXRD) methods have been used extensively to study shock phenomena for several decades [12][13][14][15][16][17][18][19][20] , with several notable successes, including the direct observation of the a À e transition in shock-compressed iron 6,21 . Some progress in understanding rapid shock-induced plasticity has been made: diffraction of monochromatic X-rays from planes parallel and perpendicular to the shock propagation direction has directly detected elastic strain in both directions (which gives a measure of plastic strain, as the total strain (elastic plus plastic) perpendicular to the shock propagation direction in a uniaxially strained material is zero) 16,[22][23][24][25] . Furthermore, broadening of the diffraction peaks observed in both shocked copper 25 , aluminium 26 and LiF 27 are consistent with large defect densities and/or lattice rotations.…”

“…Some progress in understanding rapid shock-induced plasticity has been made: diffraction of monochromatic X-rays from planes parallel and perpendicular to the shock propagation direction has directly detected elastic strain in both directions (which gives a measure of plastic strain, as the total strain (elastic plus plastic) perpendicular to the shock propagation direction in a uniaxially strained material is zero) 16,[22][23][24][25] . Furthermore, broadening of the diffraction peaks observed in both shocked copper 25 , aluminium 26 and LiF 27 are consistent with large defect densities and/or lattice rotations. However, the monochromatic diffractions techniques employed, relying solely on the observation of broadening of a Bragg peak, could not provide any information on whether such lattice rotation took place along any specifically preferred directions.…”

The Matter in Extreme Conditions instrument at the Linac Coherent Light Source

“…Such high-pressure shocks are routinely generated using highenergy laser systems in facilities around the world. Using diffraction from laser-produced X-rays to probe the changes in the microscopic structure of the material has been used very successfully over the last two decades on single crystals (see Loveridge-Smith et al, 2001;Kalantar et al, 2005;Jensen & Gupta, 2008;Murphy et al, 2010;Suggit et al, 2012, and references therein). However, the investigation of polycrystalline materials with laser-produced X-ray sources is limited in applicability due to the divergent nature of these sources and the quality of the data that can be achieved.…”

Probing dynamic material strength using in situ x-ray diffraction

“…It is the dislocations which are the fundamental quantum which governs material strength [2]. For this reason in situ x-ray diffraction (XRD) measurements are critical for understanding material strength as they give insight into the lattice level dynamics which govern the bulk material response Measurements of strength have been performed using in situ XRD on dynamically compressed single crystal copper and aluminum [3,4]. Polycrystalline materials are more commonly found in the environment and contain grain boundaries, defects, and other potential sources of dislocation generation which will make the response of the material different than in single crystal form.…”