Plastic behavior of polycrystalline tantalum in the 5 × 107/s regime

Hammel, Benjamin; Swift, Damian; El-Dasher, Bassem S.; Kumar, Mukul; Collins, G. W.; Florando, J.N.

doi:10.1063/1.3686430

Cited by 6 publications

(6 citation statements)

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“…4. Several previously reported results are also shown [9,10,41]. The figure shows that the current yield stress measurements are sensitively -dependent on the rise time in both shock and ramp compression loading such that higher yield stress obtains for a shorter rise time.…”

Section: Resultssupporting

confidence: 59%

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Dislocation Mechanics of Extremely High Rate Deformations in Iron and Tantalum

Shehadeh

Ters

Armstrong

et al. 2021

Journal of Engineering Materials and Technology

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High strain rate simulations were performed using the multiscale dislocation dynamic plasticity (MDDP) method to calculate different rise times and load durations in mimicking high deformation rate shock or isentropic (ramp) testing of a-iron and tantalum crystals. Focus for both types of loading on both materials was on the inter-relationship between the (dislocation-velocity-related) strain rate sensitivity and the (time-dependent) evolution of dislocation density. The computations are compared with model thermal activation strain rate analysis (TASRA), phonon drag and dislocation generation predictions. The overall comparison of simulated tests and previous experimental measurements shows that the imposition of a rise time even as small as 0.2 ns preceding plastic relaxation via the MDDP method is indicative of relatively weak shock behavior.

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Section: Resultssupporting

confidence: 59%

“…The rise in the strain-rate-dependent stress is greater at shorter rise times. Higher strain rates than predicted by the constitutive model of Eggert et al [9] as well as by the referenced experimental measurements [10,41] are shown to have been achieved.…”

Section: Resultsmentioning

confidence: 72%

Dislocation Mechanics of Extremely High Rate Deformations in Iron and Tantalum

Shehadeh

Ters

Armstrong

et al. 2021

Journal of Engineering Materials and Technology

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“…Further experimental details on the laser experiments can be found elsewhere. 14,15 Electron backscattered diffraction (EBSD) orientation mapping was used to characterize the texture in the samples and observe instances of twinning. To prepare samples for EBSD examination, the observed surfaces were polished to a 0.5 µm finish to minimize the surface damage.…”

Section: Methodsmentioning

confidence: 99%

Effect of strain rate and dislocation density on the twinning behavior in tantalum

et al. 2016

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The conditions which affect twinning in tantalum have been investigated across a range of strain rates and initial dislocation densities. Tantalum samples were subjected to a range of strain rates, from 10−4/s to 103/s under uniaxial stress conditions, and under laser-induced shock-loading conditions. In this study, twinning was observed at 77K at strain rates from 1/s to 103/s, and during laser-induced shock experiments. The effect of the initial dislocation density, which was imparted by deforming the material to different amounts of pre-strain, was also studied, and it was shown that twinning is suppressed after a given amount of pre-strain, even as the global stress continues to increase. These results indicate that the conditions for twinning cannot be represented solely by a critical global stress value, but are also dependent on the evolution of the dislocation density. In addition, the analysis shows that if twinning is initiated, the nucleated twins may continue to grow as a function of strain, even as the dislocation density continues to increase.

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“…Shock-loaded Ta has been studied using both gas-gun [29] and laser-driven shocks [30e32]. These experiments show a rich behavior, including high strength [32,33], dislocations [29e31], twinning above a critical pressure around 40 GPa [30,31,34,35], and the presence of uphase [30,31] in some recovered samples shocked above w70 GPa.…”

Section: Introductionmentioning

confidence: 99%