The Morphology of Tensile Failure in Tantalum

Boyce, Brad Lee; Clark, Blythe; Lu, Ping; Carroll, Jay; Weinberger, Christopher R.

doi:10.1007/s11661-013-1814-8

Cited by 36 publications

(14 citation statements)

References 28 publications

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“…In recent years, Sandia National Laboratories has conducted a series of double-blind assessments of computational predictions in the area of ductile failure of structural alloys (Boyce et al 2011). Based on these past efforts, it was clear that the double-blind evaluation methodology should be governed by some common constraints.…”

Section: Concept For a Challenge Scenariomentioning

confidence: 99%

“…High-purity single crystalline metals fail by a void nucleation process that is similar (or identical) to the failure process observed in many ductile metals. Deformation-induced subgrain structure may facilitate the nucleation of voids (Boyce et al 2012). There is clearly a need for continued investigation regarding the critical conditions that lead to void nucleation, especially in the absence of preexisting defects or hard particle interfaces.…”

Section: Failure Modelingmentioning

confidence: 99%

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The Sandia Fracture Challenge: blind round robin predictions of ductile tearing

et al. 2014

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Existing and emerging methods in computational mechanics are rarely validated against problems with an unknown outcome. For this reason, Sandia National Laboratories, in partnership with US National Science Foundation and Naval Surface Warfare Center Carderock Division, launched a computational challenge in mid-summer, 2012. Researchers and engineers were invited to predict crack initiation and propagation in a simple but novel geometry fabricated from a common off-the-shelf commercial engineering alloy. The goal of this international Sandia Fracture Challenge was to benchmark the capabilities for the prediction of deformation and damage evolution associated with ductile tearing in structural metals, including physics models, computational methods, and numerical implementations currently available in the computational fracture community. Thirteen teams participated, reporting blind predictions for the outcome of the Challenge. The simulations and experiments were performed independently and kept confidential. The methElectronic supplementary material The online version of this article (doi:10.1007/s10704-013-9904-6) contains supplementary material, which is available to authorized users.Sandia National Laboratories, Albuquerque, NM, USA e-mail: blboyce@sandia.gov ods for fracture prediction taken by the thirteen teams ranged from very simple engineering calculations to complicated multiscale simulations. The wide variation in modeling results showed a striking lack of consistency across research groups in addressing problems of ductile fracture. While some methods were more successful than others, it is clear that the problem of ductile fracture prediction continues to be challenging. Specific areas of deficiency have been identified through this effort. Also, the effort has underscored the need for additional blind prediction-based assessments.

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Section: Concept For a Challenge Scenariomentioning

confidence: 99%

Section: Failure Modelingmentioning

confidence: 99%

The Sandia Fracture Challenge: blind round robin predictions of ductile tearing

et al. 2014

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“…The FIB-prepared section bowed out into the ion beam during thinning, causing perforation in the interior of the TEM specimen. The curtaining effect is attributed to porosity introduced during the tensile test [39,40]. While the contrast in the left-hand region of this image suggests large grains, the region on the lower right appears to be very fine-grained.…”

Section: Resultsmentioning

confidence: 97%

Observations of fcc and hcp tantalum

et al. 2015

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The metal tantalum has many varied uses including in microelectronics (especially in capacitors) as thin films, in medical applications as an implant material or for surgical instruments, in X-ray lithography for masks, and in high-temperature structural applications. Ta is particularly useful because it is relatively ductile, refractory in nature, and does not readily react with corrosive materials. The body-centered cubic (bcc) crystal structure of pure Ta, also known as the a-phase, is the most commonly observed, but Ta is also known to exist in two other allotropes, one tetragonal and the other (much less-wellknown) face-centered cubic (fcc). The tetragonal form (bTa) has been produced by various deposition techniques and often occurs mixed with the a-phase; the fcc phase has only previously been reported in thin films deposited by thermal evaporation. There have been other reports of 'bcc metals' such as V and Fe existing with an fcc crystal structure when the metal is deposited as a thin film. In the present study, fcc Ta with a = 0.43 nm has been observed using transmission electron microscopy in bulk samples of Ta that have been subjected to quasi-static tensile deformation that was so large as to cause fracture of the material. The fcc phase has a relatively small grain size but appears to be stable at room temperature. It is also shown that relatively large grains (10-20 nm in diameter) of Ta can also exist with an hcp structure with a = 0.304 nm and c = 0.494 nm.

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“…This deformation mode puts the maximum stress on a surface that can be readily characterized using scanning electron microscopes and associated orientation analysis, in contrast to tensile tests, where fatal flaws usually develop unseen inside the neck region. 15 …”

Section: 10mentioning

confidence: 99%