Direct Observation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi><mml:mtext mathvariant="normal">−</mml:mtext><mml:mi>ε</mml:mi></mml:math>Transition in Shock-Compressed Iron via Nanosecond X-Ray Diffraction

Kalantar, D. H.; Belak, J.; Collins, G. W.; Colvin, J. D.; Davies, Huw M. L.; Eggert, J. H.; Germann, Timothy C.; Hawreliak, J.; Holian, Brad Lee; Kadau, Kai; Lomdahl, Peter S.; Lorenzana, H. E.; Meyers, Marc A.; Rosolanková, K.; Schneider, M.; Sheppard, J.; Stölken, James S.; Wark, J. S.

doi:10.1103/physrevlett.95.075502

Cited by 295 publications

(123 citation statements)

References 16 publications

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“…It would be interesting to see whether experimental efforts could confirm the newly predicted shock-induced β-stacking fault structure, similar to studies performed on the shock-induced phase transformations in iron. 13,14 Since the β-stacking fault structure has been found to be energetically competitive-both by the classical MEAM potential and electronic structure calculations-this might be another metastable phase that can occur during nonequilibrium conditions. Furthermore, theoretical and experimental investigation on polycrystalline Ga-similar to studies performed for iron 44 -would shed further light on the fascinating topic of shock-induced phase transformations in polymorphic materials.…”

Section: Discussionmentioning

confidence: 99%

“…11,12 Prompted by these latter simulation studies, in situ x-ray diffraction experiments subsequently confirmed the NEMD predictions for Fe single crystals compressed in the [100] crystallographic direction. [13][14][15] More recently, NEMD simulations have been used to investigate atomic-scale plastic deformation processes in more complex crystal structures beyond these relatively simple fcc, hcp, and bcc lattices. For instance, the mechanical (i.e., nonreactive) shock response of the high-explosive crystals HMX 16 and RDX 17 have been reported.…”

Section: Introductionmentioning

confidence: 99%

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Shock-induced phase transformations in gallium single crystals by atomistic methods

et al. 2013

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Utilizing a modified embedded atom method potential, we performed large-scale classical molecular dynamics simulations (with up to 50 million atoms) to investigate the response of Ga single crystals to shock compression along the three major orientations of the orthorhombic A11 ground state, i.e., [001], [010], and [100]. For weak shocks with particle velocity u p < 300 m/s, these defect-free single crystals respond elastically, but for stronger shocks, they undergo a structural phase transformation and then (for even stronger shocks) melt. For intermediate shock strengths (300 m/s < u p < 1.2 km/s) a split shock wave is formed, with an elastic precursor (uniaxial compression wave) leading the slower transformation wave. The transformed region consists of a mixed phase, with stripes of the product phase embedded into the uniaxially compressed parent phase, with the ratio of product to parent phase increasing with increasing shock strength, much like in martensitic phase transformations. Upon shock release from the free surface at the end of the sample, the transformation is reversed, leaving only some defects behind, which makes it difficult to experimentally investigate the structural transformation in shock-recovered samples. We investigated the structure produced by the shock and found it to be similar to the β phase of Ga which is obtained by supercooling from the liquid state. However, the product phase shows only half the period along [100] in the calculated diffraction pattern. Further investigation showed that this is due to a different stacking sequence in this direction, namely ABCD instead of AB for the β phase.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shock-induced phase transformations in gallium single crystals by atomistic methods

et al. 2013

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“…A lthough the shock compression of condensed matter has been a field of study for many decades [1][2][3][4][5][6] , our understanding of what occurs at the lattice level during the passage of a shock through a condensed matter system is woefully incomplete. It is well known that many simple metals, when shocked to high stresses under the constraint of uniaxial macroscopic strain, exhibit a peak stress-volume relationship (the 'PV Hugoniot') that closely follows the pressure-volume curve for hydrostatic compression.…”

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confidence: 99%

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

et al. 2012

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Under uniaxial high-stress shock compression it is believed that crystalline materials undergo complex, rapid, micro-structural changes to relieve the large applied shear stresses. Diagnosing the underlying mechanisms involved remains a significant challenge in the field of shock physics, and is critical for furthering our understanding of the fundamental lattice-level physics, and for the validation of multi-scale models of shock compression. Here we employ white-light X-ray Laue diffraction on a nanosecond timescale to make the first in situ observations of the stress relaxation mechanism in a laser-shocked crystal. The measurements were made on single-crystal copper, shocked along the [001] axis to peak stresses of order 50 GPa. The results demonstrate the presence of stress-dependent lattice rotations along specific crystallographic directions. The orientation of the rotations suggests that there is double slip on conjugate systems. In this model, the rotation magnitudes are consistent with defect densities of order 10 12 cm À 2 .

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“…The crystallographic nature of the phase was not determined until later with static compression measurements using x-ray diffraction by Jamison and Lawson [22]. It was not until recent in-situ x-ray diffraction experiments of laser shocked samples that this was confirmed [23]. With the recent success of in-situ x-ray diffraction in determining the crystal structure of shocked iron, we will use iron as the example to discuss the x-ray diffraction technique for isentropically compressed samples.…”

Section: Diffraction From Iron [100] Crystalsmentioning

confidence: 96%

Modeling Planetary Interiors in Laser Based Experiments Using Shockless Compression

Hawreliak

Colvin

Eggert

et al. 2007

High Energy Density Laboratory Astrophysics

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X-ray diffraction is a widely used technique for measuring the crystal structure of a compressed material. Recently, short pulse x-ray sources have been used to measure the crystal structure in-situ while a sample is being dynamically loaded. To reach the ultra high pressures that are unattainable in static experiments at temperatures lower than using shock techniques, shockless quasi-isentropic compression is required. Shockless compression has been demonstrated as a successful means of accessing high pressures. The National Ignition Facility (NIF), which will begin doing high pressure material science in 2010, it should be possible to reach over 2 TPa quasi-isentropically. This paper outlines how x-ray diffraction could be used to study the crystal structure in laser driven, shocklessly compressed targets the same way it has been used in shock compressed samples. A simulation of a shockless laser driven iron is used to generate simulated diffraction signals. And recently experimental results are presented.

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Direct Observation of theα−εTransition in Shock-Compressed Iron via Nanosecond X-Ray Diffraction

Cited by 295 publications

References 16 publications

Shock-induced phase transformations in gallium single crystals by atomistic methods

Shock-induced phase transformations in gallium single crystals by atomistic methods

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

Modeling Planetary Interiors in Laser Based Experiments Using Shockless Compression

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