EXAFS Measurement of Iron bcc-to-hcp Phase Transformation in Nanosecond-Laser Shocks

Yaakobi, B.; Boehly, T. R.; Meyerhofer, D. D.; Collins, T. J. B.; Remington, B. A.; Allen, P. G.; Pollaine, S. M.; Lorenzana, H. E.; Eggert, J. H.

doi:10.1103/physrevlett.95.075501

Cited by 111 publications

(42 citation statements)

References 26 publications

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“…Well known concepts of phase nucleation and growth are being revisited and refined [1][2][3] due to their importance in geophysics, metallurgy, materials science [4][5][6][7] and many other fields, while new experimental techniques, particularly at high pressures, continue to open new vistas of research and exploration [8][9][10][11][12][13][14]. The study of phase transition kinetics under high pressures has a long history, with the earliest reported measurements being performed under static conditions by Bridgman [15].…”

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confidence: 99%

High pressure phase transformation in iron under fast compression

Bastea

Becker

2009

Applied Physics Letters

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We observe kinetic features—velocity loops—at the α to ϵ phase transformation of iron, similar with the ones reported when water is frozen into its ice VII phase under comparable experimental conditions. By using a phase nucleation and growth kinetic model with pressure dependent phase interface velocity we find that the thermodynamic path followed by the sample is strongly dependent on the drive conditions and sample characteristics. The velocity loops become broader and shallower at slower compressions, while on faster time–scales, e.g., for laser drivers, the loops form at higher velocities and may eventually disappear.

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confidence: 99%

High pressure phase transformation in iron under fast compression

Bastea

Becker

2009

Applied Physics Letters

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“…From the experimental side, conventional transmission electron microscopy (TEM) can record snapshots of the process, but with a millisecond resolution at fastest. 22 We note that the effects of laser pulse irradiation on an Fe specimen have previously been reported to induce phase changes by a sudden temperature jump 23,24 or gigantic pressure, 25,26 but observations in these studies were made only to postevent microstructures by the use of continuouswave probes, missing detailed information on the mechanism of phase-change dynamics. On the other hand, a timeresolved study has been carried out on Fe thin films by highspeed TEM imaging with ns laser heating.…”

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Direct Observation of Martensitic Phase-Transformation Dynamics in Iron by 4D Single-Pulse Electron Microscopy

et al. 2009

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The in situ martensitic phase transformation of iron, a complex solid-state transition involving collective atomic displacement and interface movement, is studied in real time by means of four-dimensional (4D) electron microscopy. The iron nanofilm specimen is heated at a maximum rate of approximately 10(11) K/s by a single heating pulse, and the evolution of the phase transformation from body-centered cubic to face-centered cubic crystal structure is followed by means of single-pulse, selected-area diffraction and real-space imaging. Two distinct components are revealed in the evolution of the crystal structure. The first, on the nanosecond time scale, is a direct martensitic transformation, which proceeds in regions heated into the temperature range of stability of the fcc phase, 1185-1667 K. The second, on the microsecond time scale, represents an indirect process for the hottest central zone of laser heating, where the temperature is initially above 1667 K and cooling is the rate-determining step. The mechanism of the direct transformation involves two steps, that of (barrier-crossing) nucleation on the reported nanosecond time scale, followed by a rapid grain growth typically in approximately 100 ps for 10 nm crystallites.

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“…Because of the transient and reversibility of this transition, it is not until recent decade that direct experimental observations of the phase transition under shock compressions are available (Kalantar et al, 2005;Wang et al, 2013;Yaakobi et al, 2005). Combined with non-equilibrium molecular dynamics (NEMD) simulations, phase transition mechanism has been well established for single crystalline iron under the shock along different crystallographic orientations (Hawreliak et al, 2006;Wang et al, 2014a).…”

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confidence: 99%