Spin Effects in Plasticity

Molotskii, M.; Fleurov, V.

doi:10.1103/physrevlett.78.2779

Cited by 71 publications

(64 citation statements)

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“…The theories not only cannot be expressed one through other, but they also do not exclude one another. So, for example, thermal expansion at big rate, that is told of by Bilyk et al and Unger et al [34,35], does not prohibit the magnetic field influence upon the spins of dopants and pinned dislocation cores, that are involved in Molotskii's model [32][33][34]. Other mechanisms are also not discarded.…”

Section: Resultsmentioning

confidence: 99%

“…The second subsection deals with the Michel Molotskii's theory, which is presented in his articles [32][33][34]. In his earlier works, Molotskii considered the influence of magnetic field on the interaction of dislocations with paramagnetic dopants-stoppers.…”

Section: Comparison Of Different Theoretical Models With Experimentalmentioning

confidence: 99%

“…Michel Molotskii in his works [32][33][34] proposes the following model of the influence of magnetic field upon the plastic properties of the material. Electroplastic effect, according to Molotskii, is a particular manifestation of magnetoplastic effect, when the magnetic field is created by the electric current.…”

Section: Influence Of the Electric Current Density On The Plasticizatmentioning

confidence: 99%

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Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Karas

Karasyova

Mats

et al. 2016

Metallofiz. Noveishie Tekhnol.

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The results of the investigation of creep characteristics and activation parameters of polycrystalline nickel (of 99.996% purity) plastic flow at the temperature of 77 K are presented. The influence of nonstationary magnetic field with strength of 500 Oe (harmonic (50 Hz) and monopolar pulses of the same frequency) on the nickel creep characteristics is studied. We have deliberately conducted experimental investigations of the influence of nonstationary magnetic field of alternating and constant sign at constant temperature in order to estimate the contribution to the dislocations' mobility from the interaction of dislocations with the mobile domain boundaries as well as from the heat effects connected with the induction electric field. The proposed model of electroplastic effect (EPE) suggests the following mechanism of weakening under the action of electric field. Electric field gives energy to conductivity electron subsystem, making it thermodynamically nonequilibrium. Nonequilibrium electrons while interacting with acoustic phonons transfer more energy to short-wave part of the phonon spectrum. Short-wave phonons due to large stress gradient effectively detach dislocations from stoppers. Experimental results qualitatively match with the data obtained after numerical calculations.Key words: magnetoplastic effect, alternating magnetic field, dislocation mobility, creep rate, ferromagnetic crystal, nonequilibrium electron and phonon subsystem.Наведено результати досліджень характеристик плазучости та актива-ційних параметрів пластичної течії полікристалічного ніклю (99,996% чистоти) за постійної температури у 77 К. Досліджувався вплив нестаціо-нарного магнетного поля напруженістю у 500 Е (гармонічні (50 Гц) та од-нополярні імпульси тієї ж частоти) на параметри плазучости ніклю. Екс-периментальні дослідження з впливу нестаціонарного магнетного поля змінного та сталого знаку за постійної температури проводилися, щоб оцінити внесок у рухливість дислокацій від взаємодії дислокацій з рух-ливими межами домен, а також від теплових ефектів, пов'язаних з індук-ційним електричним полем. Пропонований модель електропластичного ефекту (ЕПЕ) передбачає наступний механізм знеміцнення під дією елек-тричного поля. Електричне поле передає енергію підсистемі електронів провідности, роблячи її термодинамічно нерівноважною. Нерівноважні електрони, що взаємодіють з акустичними фононами, передають енергію переважно короткохвильовій частині фононного спектру. Короткохви-льові фонони, завдяки великому ґрадієнту напруги, ефективно відкріп-люють дислокації від стопорів. Результати експериментів якісно збіга-ються з даними числових розрахунків.Ключові слова: магнетопластичний ефект, змінне магнетне поле, рухли-вість дислокацій, швидкість плазучости, феромагнетний кристал, нерів-новажна електронна та фононна підсистеми.Представлены результаты исследования характеристик ползучести и ак-тивационных параметров пластического течения поликристаллического никеля (99,996% чистоты) при температуре 77 К. Было изучено влияние нестационарного магнитн...

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Section: Resultsmentioning

confidence: 99%

Section: Comparison Of Different Theoretical Models With Experimentalmentioning

confidence: 99%

Section: Influence Of the Electric Current Density On The Plasticizatmentioning

confidence: 99%

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Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Karas

Karasyova

Mats

et al. 2016

Metallofiz. Noveishie Tekhnol.

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“…On the other hand, it is well known that the dangling bonds at the defect core could introduce localized electronic states and magnetic moments. 3,7,8 In some cases, these defects could eventually lead to magnetic ordering. Therefore, the interplay between magnetism and lattice defects-lattice defects could give rise to magnetism and magnetism could affect the properties of lattice defects, offers an intriguing perspective that could be useful in the design of novel materials.…”

mentioning

confidence: 99%

“…They showed that the applied magnetic field could then induce transitions between different spin states of such pairs characterized by different binding energies, and thus facilitate dislocation depinning from the impurity and enhance the crystal plasticity. 3 Despite its physical significance, the magnetoplasticity phenomenon becomes less relevant in most applications where materials deform in the absence of an applied magnetic field. However, a recent work combining theory and experiments 4,5 has shown that even in the absence of the magnetic field, magnetism plays an important role in the mechanical response of materials.…”

mentioning

confidence: 99%

Magnetism-driven dislocation dissociation, cross slip, and mobility in NiAl

2010

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We have examined the interplay between magnetism and dislocation core properties in NiAl alloys using quantum mechanics/molecular mechanics simulations. We observe the magnetism-driven site preference of Fe and Co impurities at the dislocation core. When occupying the Ni sublattice, Fe and Co impurities are found to induce spontaneous dislocation cross slip. When occupying the Al sublattice, the impurities render the originally undissociated dislocation to split into two partials. Finally we observe the magnetism-driven dislocation mobility when Fe impurity occupies the Al sublattice, which has also been discovered experimentally. The magnetic interaction between the impurities and the host atoms is responsible for the significant changes in the dislocation core structure and mobility. DOI: 10.1103/PhysRevB.82.060404 PACS number͑s͒: 75.30.Hx, 61.72.Lk, 61.72.Nn, 71.20.Lp It has been shown experimentally that an applied magnetic field can change the plastic behavior of crystalline materials, a phenomenon known as magnetoplasticity.1,2 In a series of theoretical papers, Molotskii and Fleurov have explained the phenomenon by assuming that a dangling bond of a paramagnetic impurity forms a radical pair with a dangling bond of the dislocation core. They showed that the applied magnetic field could then induce transitions between different spin states of such pairs characterized by different binding energies, and thus facilitate dislocation depinning from the impurity and enhance the crystal plasticity.3 Despite its physical significance, the magnetoplasticity phenomenon becomes less relevant in most applications where materials deform in the absence of an applied magnetic field. However, a recent work combining theory and experiments 4,5 has shown that even in the absence of the magnetic field, magnetism plays an important role in the mechanical response of materials. In particular, it is discovered that 3d transitionmetal impurities ͑Fe, Co, Ni, Cr, etc.͒ could profoundly change the mechanical properties of B2-NiAl intermetallic alloys; the origin of the impurity-induced solid solution softening in these alloys is due to the magnetic interaction between the impurities and the host atoms. 6 The experimentally observed softening can only be reproduced by densityfunctional theory ͑DFT͒ calculations if the magnetic interaction ͑or spin polarization͒ is turned on. Similarly, the site preference and lattice spacing changes would switch sign if the spin polarization is turned off in the DFT calculations. These results along with the magnetoplasticity effect, highlight the important role that magnetism plays in the mechanical response of materials, illustrating the cross fertilization between two disciplines, magnetism and mechanical properties.B2 intermetallic NiAl alloys have attracted a lot of attention recently owing to their potential applications as hightemperature structural materials. One of the common practices to improve the mechanical properties of materials is alloying. For example, introducing substitutiona...

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Magnetic Field‐Assisted Laser Shock Peening of Ti₆Al₄V Alloy

Qian

Cai

et al. 2023

Adv Eng Mater

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Laser shock peening is widely used in mechanical property improvements of metallic materials. One concerning factor is the nonuniformity of mechanical properties and microstructures, such as surface hardness and grain refinement. Herein, a new strengthening strategy that integrates femtosecond laser shock peening and pulse magnetic field that can uniformize the performance of metallic materials is proposed. With the magnetic field‐assisted laser shock peening (MFLSP), the reduction of preferred‐clustering points shows uniform grain refinement with the maximum area fraction of small grains. The fabrication of uniform grain refinement is attributed to the dislocation redistribution by the release of pinning effect. With magnetic field stimulation, dislocation lines are observed to disperse from low‐angle grain boundary to the intragranular area. Dislocation behaviors stimulated by magnetic field are attributed to atomic migration. The dispersed dislocations serve as potential glide sources for grain refinement during laser‐induced plastic deformation. The enhanced grain refinement results in uniform surface hardening of metallic materials. The application of this integrated strategy with laser processing and external energy field can be used for adjusting mechanical properties of metallic materials with uniform microstructures and surface hardness.

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Spin Effects in Plasticity

Cited by 71 publications

References 6 publications

Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Magnetism-driven dislocation dissociation, cross slip, and mobility in NiAl

Magnetic Field‐Assisted Laser Shock Peening of Ti₆Al₄V Alloy

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Spin Effects in Plasticity

Cited by 71 publications

References 6 publications

Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals

Magnetism-driven dislocation dissociation, cross slip, and mobility in NiAl

Magnetic Field‐Assisted Laser Shock Peening of Ti6Al4V Alloy

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Magnetic Field‐Assisted Laser Shock Peening of Ti₆Al₄V Alloy