Coupled strain-induced alpha to omega phase transformation and plastic flow in zirconium under high pressure torsion in a rotational diamond anvil cell

dc.contributor.author Feng, Biao
dc.contributor.author Levitas, Valery
dc.contributor.author Kamrani, Mehdi
dc.contributor.department Aerospace Engineering
dc.contributor.department Ames National Laboratory
dc.contributor.department Mechanical Engineering
dc.contributor.department Materials Science and Engineering
dc.date 2018-06-28T04:28:02.000
dc.date.accessioned 2020-06-29T22:45:24Z
dc.date.available 2020-06-29T22:45:24Z
dc.date.copyright Mon Jan 01 00:00:00 UTC 2018
dc.date.embargo 2019-07-19
dc.date.issued 2018-01-01
dc.description.abstract <p>Strain-induced α→ω phase transformation (PT) in the zirconium (Zr) sample under compression and plastic shear in a rotational diamond anvil cell (RDAC) is investigated using the finite element method (FEM). The fields of the volume fraction of the ω phase, all components of the stress tensor, and plastic strain are presented. Before torsion, PT barely occurs. During torsion under a fixed applied force, PT initiates at the center of the sample, where the pressure first reaches the minimum pressure for strain-induced α→ω PT,<a title="View the MathML source"></a>, and propagates from the center to the periphery and from the symmetry plane to the contact surface. Salient increase of the shear friction stress and pressure at the center of a sample, so-called pressure self-multiplication effect observed experimentally for some other materials, is predicted here for Zr. It is caused by much higher yield strength of the ω phase in comparison with the α phase. Except at the very center of a sample, the total contact friction stress is equal to the yield strength in shear of the mixture of phases and the plastic sliding occurs there. Due to the reduction in sample thickness and radial material flow during torsion, the ω phase can be observed in the region where pressure is lower than <a title="View the MathML source"></a>, which may lead to misinterpretation of the experimental data for <a title="View the MathML source"></a>. For the same applied force, torsion drastically promotes PT in comparison with the compression without torsion. However, the PT process in RDAC is far from optimal: (a) due to the pressure self-multiplication effect, the pressure in the transformed region is much higher than that required for PT; (b) the region in which PT occurs is limited by the pressure <a title="View the MathML source"></a> and cannot be expanded by increasing a shear under a fixed force; and (c) the significant reduction in thickness during torsion reduces the total mass of the high-pressure phase. These drawbacks can be overcome by placing a sample within a strong gasket with an optimized geometry. It is shown that, due to strong pressure heterogeneity, characterization of α→ω and α→β PTs based on the averaged pressure contains large errors. The obtained results, in addition to providing an improved understanding of the strain-induced PTs, may be beneficial for the optimum design of experiments and the extraction of material parameters, as well as optimization and control of PTs by varying the geometry and loading conditions.</p>
dc.description.comments <p>This is a manuscript of an article published as Feng, Biao, Valery I. Levitas, and Mehdi Kamrani. "Coupled strain-induced alpha to omega phase transformation and plastic flow in zirconium under high pressure torsion in a rotational diamond anvil cell." <em>Materials Science and Engineering: A</em> (2018). doi: <a href="http://dx.doi.org/10.1016/j.msea.2018.06.061" target="_blank">10.1016/j.msea.2018.06.061</a>. Posted with permission.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/aere_pubs/122/
dc.identifier.articleid 1123
dc.identifier.contextkey 12367839
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath aere_pubs/122
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/1966
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/aere_pubs/122/2018_Levitas_CoupledStrain.pdf|||Fri Jan 14 19:15:33 UTC 2022
dc.source.uri 10.1016/j.msea.2018.06.061
dc.subject.disciplines Aerospace Engineering
dc.subject.disciplines Materials Science and Engineering
dc.subject.disciplines Structural Materials
dc.subject.disciplines Structures and Materials
dc.subject.keywords Strain-induced phase transformations
dc.subject.keywords Zirconium
dc.subject.keywords High pressure
dc.subject.keywords Rotational diamond anvil cell
dc.subject.keywords Plasticity
dc.title Coupled strain-induced alpha to omega phase transformation and plastic flow in zirconium under high pressure torsion in a rotational diamond anvil cell
dc.type article
dc.type.genre article
dspace.entity.type Publication
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