The energy landscape of screw dislocation cores plays a central role in dislocation-mediated deformation mechanisms in body-centered cubic (bcc) metals. In bcc high-entropy alloys (HEAs), this energy landscape is modulated by local compositional fluctuations, which has important implications for deformation processes in these materials. Through first-principles calculations, this study investigates high-symmetry screw dislocation core structures in NbTaMoW and NbTaTiHf bcc HEAs. The results show that alloying group IV transition metals lead to large local lattice distortions at dislocation cores, which is demonstrated to be an important factor governing fluctuations in core configurations along a dislocation line. Importantly, group IV elements near the core induce features in the energy landscape that are exclusive for HEAs, specifically lowering the energy of core configurations that are unstable in elemental bcc metals. A combined influence of these chemical effects with crystallographic details enables the activation of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mo>{</a:mo><a:mn>112</a:mn><a:mo>}</a:mo></a:mrow></a:math> glide planes, a feature that has been linked to ductility improvements in bcc HEAs. These findings provide new insights into the atomic-scale mechanisms underlying dislocation mobility in bcc HEAs, offering a pathway for designing materials with tailored mechanical properties.
10.1149/1.2978244
(1) University of Edinburgh, School of GeoSciences, Edinburgh, United Kingdom (paul.stoy@ed.ac.uk), (2) Complex Systems Research Center, University of New Hampshire, Morse Hall, 39 College Road, Durham, NH 03824, USA, (3) Department of Environmental Science, Policy and Management, University of California at Berkeley, USA, (4) Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708, USA, (5) Max Planck Institute for Biogeochemistry, PO Box 10 01 64, 07701 Jena, Germany, (6) Department of Forest Science, Oregon State University, Corvallis, OR, USA, (7) Servizi Forestali, Agenzia per l Ambiente, Provincia Autonoma di Bolzano, Bolzano, Italy, (8) Institut fur Botanik, Universitat Innsbruck, Austria
We propose controllable unidirectional anti-laser in a one dimensional coupled cavities where an interplay between Fano resonances and a judicious absorption mechanism leads to a unidirectional perfect absorber.
[Fassett et al. (2011][1], herein) analyzed fossil bone fragments from the San Juan Basin of New Mexico and claim to have achieved the “first successful direct dating of fossil vertebrate bone” (p. 159). This claim is asserted to establish the survival of dinosaurs into the Paleogene, thus
SUMMARY A study was carried out on two cases of reflex epilepsy with hemiconvulsive seizures induced by proprioceptive stimulations (tuning fork vibrations and active and/or passive movements). A proprioceptive dissociation is shown to exist in reflex epilepsy, i.e. the seizures are induced only by certain proprioceptive stimuli (vibration or movement). It is assumed that the proprioceptive stimuli generated during the convulsive seizure intervene by a feedback mechanism. By means of this feedback mechanism the afferent proprioceptive impulses in the course of the seizure facilitate the cortical mechanisms of clonic transformation of the convulsive fit. Interruption of this mechanism in the clonic phase of the paroxysm by immobilization of the parts showing myoclonic jerks brought about immediate arrest of the seizure in the first case and temporary disappearance of the spontaneous focal discharges during the seizure in the second case. RÉSUMÉ Les auteurs présentent deux cas d'épilepsie réflexe avec des crises hémiconvulsives provoquées par des stimulations proprioceptives (les vibrations d'un diapason et les mouvements passifs ou actifs). On a observé une dissociation proprioceptive au cours des crises, provoquées seulement par certaines stimulations proprioceptives (vibrations ou mouvements). On suppose que les stimulations proprioceptives apparaissant au cours des crises interviennent par un mécanisme de feedback. Par ce mécanisme les impulsions afférentes proprioceptives interviennent au niveau cortical, facilitant la transformation clonique des crises convulsives. L'interruption de ces mécanismes dans sa phase clonique par l'immobilisation du segment animé de mouvements myocloniques a provoqué un arrêt immédiat de la crise dans notre premier cas et une disparition de courte durée des décharges focales spontanées dans notre deuxième cas.
Dieter Vandebroeck (DV): É conhecido pela sua elucidação e elaboração das teorias de Pierre Bourdieu, mas sobretudo pela sua “etnografia carnal” do boxe e pelas suas incursões no “triângulo mortal” de classe, raça e Estado penal na metrópole dual. Contudo, os leitores não estão familiarizados com a viagem biográfica e académica que o levou à zona sul de Chicago, o local principal dos seus estudos. Poderia traçar o seu caminho para as ciências sociais: a sua formação inicial como economista in...
A theory of elastically rigid finite deformation plasticity emphasizing the role of material symmetry is developed. The fields describing lattice rotation, dislocation density and plastic spin, irrelevant in the case of isotropy, are found to be central to the present framework. A plane strain characteristic theory for anisotropic plasticity is formulated wherein the solutions, as well as the nature of their discontinuities, show remarkable deviation from the classical isotropic slipline theory.
