Dynamic Equation of State and Strength of Boron Carbide

Grady, D. E.

doi:10.1002/9780470944004.ch12

Cited by 9 publications

(10 citation statements)

References 22 publications

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“…The shock strength properties of BC have been reported by Gust and Royce, Wilkins, Pavlovski, Zhang et al., McQueen et al., Vogler et al.,, and Grady . However, due to variation in composition, porosity, density, and experimental technique, a clear understanding of the dynamic response of BC has proven difficult to obtain . Vogler et al .…”

Section: Introductionmentioning

confidence: 93%

“…A shock induced phase transition can also be inferred from the Hugoniot data of McQueen et al . This data set, as discussed by Grady, is often disregarded due to the high porosity of the experimental samples used in that work which resulted in significant disagreement with results obtained in other studies. However, the insightful data analysis reported by Grady showed that the McQueen et al .…”

Section: Introductionmentioning

confidence: 97%

“…This data set, as discussed by Grady, is often disregarded due to the high porosity of the experimental samples used in that work which resulted in significant disagreement with results obtained in other studies. However, the insightful data analysis reported by Grady showed that the McQueen et al . results are indeed consistent with other shock measurements when the data are normalized to account for porosity.…”

Section: Introductionmentioning

confidence: 99%

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Shock Compression of Boron Carbide: A Quantum Mechanical Analysis

Taylor

2015

J. Am. Ceram. Soc.

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The shock Hugoniot of boron carbide, from 0 to 80 GPa, has been obtained using first principles quantum mechanics (density functional theory) and molecular dynamics simulation. The Hugoniot for six different structures which vary by structure or stoichiometry were computed and compared to experimental data. The effect of stoichiometry, and structural variation within a given stoichiometry, are shown to have marked effects on the shock properties with some compositions displaying bilinear behavior in the computed shock velocity‐particle velocity profiles while others show a continuous Hugoniot curve with no evidence of a phase transition over the pressure range considered in this work. Two structures, B12(CBC) and B11Cp(CCB), have predicted phase transition pressures lying within the 40–50 GPa range suggested experimentally. It is shown that the phase transition is driven by deformation of the 3‐atom chain within the boron carbide crystal structure which induces a discontinuous volume change at the critical shock pressure. The effect of defects, in the form of chain vacancies, on the shock response is presented and the ability of shear to significantly lower the phase transition pressure, in accord with experimental observation, is demonstrated.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Shock Compression of Boron Carbide: A Quantum Mechanical Analysis

Taylor

2015

J. Am. Ceram. Soc.

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“…Raman spectra up to 50 GPa 22,23 and X-ray diffraction measurements up to 126 GPa 24 have not observed any evidence indicative of a structural phase transition. Under dynamic compression (until recently 25 equation of states (EOS) data from shock compression have been available up to pressures of 200 GPa 4,5,[26][27][28][29][30][31][32][33][34][35] ) the behavior is more complex. Anomalies in the shock Hugoniot that are found between 20-60 GPa are suggestive of a phase transition 36 .…”

Section: Introductionmentioning

confidence: 99%

Properties of B4C in the shocked state for pressures up to 1.5 TPa

et al. 2017

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Density Functional Theory calculations using the quasi-harmonic approximation have been used to calculate the solid Hugoniot of two polytypes of boron carbide up to 100 GPa. Under the assumption that segregation into the elemental phases occurs around the pressure that the B11Cp(CBC) polytype becomes thermodynamically unstable with respect to boron and carbon, two discontinuities in the Hugoniot, one at 50 GPa and one at 90-100 GPa, are predicted. The former is a result of phase segregation, and the latter a phase transition within boron. First principles molecular dynamics (FPMD) simulations were employed to calculate the liquid Hugoniot of B4C up to 1.5 TPa, and the results are compared to recent experiments carried out at the Omega Laser Facility up to 700 GPa [Phys. Rev. B 94, 184107 (2016)]. A generally good agreement between theory and experiment was observed. Analysis of the FPMD simulations provides evidence for an amorphous, but covalently bound, fluid below 438 GPa, and an atomistic fluid at higher pressures and temperatures.

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“…Neither quasistatic highpressure nor shock wave testing, however, has uncovered unambiguous evidence for phase transformation in boron carbide. Nonetheless, unusual features in the shock Hugoniot of boron carbide lend tentative support for phase transformation in the dynamic event [52]. The previous studies on boron carbide do not explore the possibility of adiabatic shear in the deformation processes leading to the observed amorphous deformation features.…”

Section: Adiabatic Shear In Brittle Solidsmentioning

confidence: 89%