<i>In situ</i>lattice measurement of the bcc phase boundary in Mg on the principal shock Hugoniot

Milathianaki, Despina; Swift, Damian; Hawreliak, J.; El-Dasher, Bassem S.; McNaney, J. M.; Lorenzana, H. E.; Ditmire, T.

doi:10.1103/physrevb.86.014101

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…Therefore, the plasticity prior to the phase transition takes place as expected in the experiments. [3][4][5][8][9][10]15) According to the microstructures, we find that the phase transition does not happen uniformly either among different grains or within an individual grain under a weak loading strength, which is well consistent with the coexistence region in experiments of Mg under high pressure. [14][15][16] The dynamics for the shock compression is reflected in the longitudinal pressure profiles, particularly in the relaxation of the shear stress.…”

Section: Yy Zzsupporting

confidence: 83%

“…In the 1980s, Olijnyk and Holzapfel firstly found the BCC structure in Mg by energydispersive X-ray diffraction at room temperature when the pressure was around 50 GPa through the linear compression. 14) Since then, a series of work was carried on phase transition of single crystal Mg in experiments 15,16) and theories. [17][18][19][20][21] For example, Milathianaki et al 15) investigated the phase transition of pure Mg under high pressure using single laser pulses, and found the coexistence region of HCP and BCC.…”

mentioning

confidence: 99%

“…14) Since then, a series of work was carried on phase transition of single crystal Mg in experiments 15,16) and theories. [17][18][19][20][21] For example, Milathianaki et al 15) investigated the phase transition of pure Mg under high pressure using single laser pulses, and found the coexistence region of HCP and BCC. However, little attention is paid to the phase-transition process under shock compression and the coupling of the plasticity and phase transition in Mg polycrystalline under high-pressure shock.…”

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confidence: 99%

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Molecular dynamic simulations of plasticity and phase transition in Mg polycrystalline under shock compression

Jian¹,

Chen²,

Xiao³

et al. 2022

Appl. Phys. Express

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We have investigated the shock-induced plasticity and phase transition in the hexagonal columnar nanocrystalline (HCN) Mg by large-scale nonequilibrium molecular dynamics simulations (NEMD). The preexisting grain boundaries (GBs) induce the nucleation of the {10-12} twins for the local stress relaxation. The twins grow up in grains leading to the orientation rotation. The phase transition from the hexagonal close-packed (HCP) phase to the body-centered cubic (BCC) phase begins when the migrating twin grain boundaries (TGBs) meet in A- and C-type grains, and continues in the plastic deformation regions. The phase-transition pathway involves two steps: the reorientation and phase transformation.

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Section: Yy Zzsupporting

confidence: 83%

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confidence: 99%

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confidence: 99%

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Molecular dynamic simulations of plasticity and phase transition in Mg polycrystalline under shock compression

Jian¹,

Chen²,

Xiao³

et al. 2022

Appl. Phys. Express

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“…just above the HEL) as an intensitythreshold plot around the origin for a region in reciprocal space bounded by points with Miller indices (±3, ±3, ±3. 45), where the indices are referenced to the ambient unshocked material. At this shock pressure the crystal has been compressed to 87% of its original volume.…”

Section: Resultsmentioning

confidence: 99%

Molecular dynamics simulations of inelastic x-ray scattering from shocked copper

Karnbach

Heighway

McGonegle

et al. 2021

Journal of Applied Physics

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By taking the spatial and temporal Fourier transforms of the coordinates of the atoms in molecular dynamics simulations conducted using an embedded-atom-method potential, we calculate the inelastic scattering of x-rays from copper singlecrystals shocked along [001] to pressures of up to 70 GPa. Above the Hugoniot elastic limit (HEL), we find that the copious stacking faults generated at the shock front introduce strong quasi-elastic scattering (QES) that competes with the inelastic scattering signal, which remains discernible within the first Brillouin zone; for specific directions in reciprocal space outside the first zone, the QES dominates the inelastic signal overwhelmingly. The synthetic scattering spectra we generate from our Fourier transforms suggest that energy resolutions of order 10 meV would be required to distinguish inelastic from quasi-elastic scattering within the first Brillouin zone of shock-loaded copper. We further note that high-resolution inelastic scattering also affords the possibility of directly measuring particle velocities via the Doppler shift. These simulations are of relevance to future planned inelastic scattering experiments at x-ray Free Electron Laser (FEL) facilities.

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“…In turn, the presence of a Hugoniot discontinuity may provide an indication of a phase transition within the material. However, these methods may fail for solid-liquid transitions (or melting) (Hayes et al, 1999) and solid-solid transitions with expected volume collapses of less than 1%, such as the hexagonal close-packed to body-centred cubic transition in magnesium (Milathianaki et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Iterative diffraction pattern retrieval from a single focal construct geometry image

Chen¹,

Xue²,

Tan³

et al. 2021

J Appl Cryst

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Understanding the crystal structure of materials under extreme conditions of pressure and temperature has been revolutionized by major advances in laser-driven dynamic compression and in situ X-ray diffraction (XRD) technology. Instead of the well known Debye–Scherrer configuration, the focal construct geometry (FCG) was introduced to produce high-intensity diffraction data from laser-based in situ XRD experiments without increasing the amount of laser energy, but the resulting reflections suffered from profoundly asymmetrical broadening, leading to inaccuracy in determination of the crystal structure. Inspired by fast-neutron energy spectrum measurements, proposed here is an iterative retrieval method for recovering diffraction data from a single FCG image. This iterative algorithm restores both the peak shape and relative intensity with rapid convergence and requires no prior knowledge about the expected diffraction pattern, allowing the FCG to increase the in situ XRD intensity while simultaneously preserving the angular resolution. The feasibility and validity of the method are shown by successful recovery of the diffraction pattern from both a single simulated FCG image and a single laser-based nanosecond XRD measurement.

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In situlattice measurement of the bcc phase boundary in Mg on the principal shock Hugoniot

Cited by 15 publications

References 27 publications

Molecular dynamic simulations of plasticity and phase transition in Mg polycrystalline under shock compression

Molecular dynamic simulations of plasticity and phase transition in Mg polycrystalline under shock compression

Molecular dynamics simulations of inelastic x-ray scattering from shocked copper

Iterative diffraction pattern retrieval from a single focal construct geometry image

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