Dislocation dragging by electrons in metals

Kaganov, M.I.; Kravchenko, Ya. V.; Нацик, В. Д.

doi:10.1070/pu1974v016n06abeh004096

Cited by 71 publications

(15 citation statements)

References 44 publications

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“…20,21,26 A comparison of the values of the residual resistivity of a metallic sample initially deformed in the normal state and then in the superconducting state, under otherwise identical conditions of deformation ͑temperature, rate, and total deformation͒, has shown that the rate of accumulation of the deformation defects responsible for the increased resistivity of the sample is significantly higher in the superconducting state than in the normal state. Since the gliding dislocations in a superconducting crystal move at higher velocities in the superconducting state, 4,7,14,15 the number of such crossing events per unit time is larger than in the normal state. The source of point defects ͑vacancies and interstitial atoms͒ was assumed to be mobile jogs formed on gliding dislocations as they cross "forest" dislocations.…”

Section: E Influence Of the Superconducting Transition On The Work Hmentioning

confidence: 99%

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Quantum creep of β–Sn in the normal and superconducting states. Influence of the NS transition on work hardening

Нацик

Soldatov

Ivanchenko

et al. 2006

Low Temperature Physics

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Previously we investigated the kinetics of transient logarithmic creep of ␤-tin single crystals at very low temperatures 0.5 K Ͻ T Ͻ 4.2 K with the sample under deformation in the normal ͑N͒ electronic state. In a continuation of that research, here we determine the boundary temperature T g Ϸ 1.3 K separating the regions of thermally activated ͑T Ͼ T g ͒ and quantum ͑T Ͻ T g ͒ plasticity governed by the motion of dislocations through Peierls barriers. Experiments are done on samples in the superconducting ͑S͒ state ͑0.5 K Ͻ T Ͻ T c = 3.7 K͒. It is shown that the NS transition preserves the logarithmic type of creep, its quantum character in the region T Ͻ T g , and the value of the boundary temperature ͑T gS Ϸ T gN Ϸ 1.3 K͒. Analysis of the curves of the logarithmic creep in the quantum region can yield empirical estimates for the work hardening coefficient of the samples. It is found to increase significantly at the NS transition: along the whole deformation curve the work hardening in the S state occurs more intensely, and, on the average, S Ϸ 1.5 N . Such an effect has been observed previously in a study of the plasticity of a series of fcc metals by the method of active deformation at a constant rate ͑V. V. Pustovalov, I. N. Kuz'menko, N. V. Isaev, V. S. Fomenko, S. É. Shumlin, Fiz. Nizk. Temp. 30, 109 ͑2004͒ ͓Low Temp. Phys. 30, 82 ͑2004͔͒͒. A comparison of the results of this study with previous results suggests that the increase in intensity of the work hardening at the superconducting transition is of a general nature for metallic superconductors and is manifested for other deformation regimes as well. The possible causes of the effect are discussed in the general conceptual framework of dislocation physics.

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Section: E Influence Of the Superconducting Transition On The Work Hmentioning

confidence: 99%

“…7 According to present-day ideas of the physics of plasticity, electronic friction can have a substantial influence on both the kinetics of the overcoming of lattice barriers or impurity barriers by dislocations 3,8-10 and on the dynamics of their above-barrier motion. This problem is of interest for several reasons.…”

Section: Introductionmentioning

confidence: 99%

Quantum creep of β–Sn in the normal and superconducting states. Influence of the NS transition on work hardening

Нацик

Soldatov

Ivanchenko

et al. 2006

Low Temperature Physics

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“…53 The problem of the interaction between dislocations and conduction electrons has also been studied for its role in the plasticity of normal metals and superconductors. 54 The influence of external fields on the dislocation mobility has been investigated in Refs. 18 and 55-57.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of electromagnetic emission in plastically deformed ionic crystals

et al. 2007

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Experiments on the plastic deformation of LiF ionic monocrystals under uniaxial compression are performed with simultaneous recording of acoustic ͑AE͒ and electromagnetic ͑EME͒ emissions. A strong correlation between AE and EME events has been found, which clearly demonstrates that the observed EME is caused by a dynamical interaction between moving dislocations and charged vacancies in the ionic lattice during work hardening. The mechanism proposed to explain EME is based on the assumption that gliding edge dislocations sweep up the vacancies of a preferable sign. As a result, when a dislocation pileup is formed, a certain nonequilibrium charge density is accumulated at its head, resulting in electric polarization of the deformed crystal. As the external loading increases, a locked dislocation pileup bursts through the stoppers and quickly loses its bounded charge. The relaxation of this charge produces an intrinsic polarization current generating an electric pulse. It is assumed that the relaxation current can be described as an athermic viscous motion of vacancies under the kinetic friction force ϳBv ͑B is the friction coefficient and v is the vacancy velocity͒ in a self-consistent electric field determined by the distribution of the total charge density. A nonlinear integrodifferential equation of motion for the nonequilibrium charge density is derived. For a special form of the initial charge density distribution, an automodel solution of this equation describing the polarization current has been built. The electrical signal generated by an acting slip system has been calculated. By comparing the calculated and experimentally measured electric signal patterns, the friction coefficient for the linear chain of vacancies ͑the analog of an edge dislocation extra plane͒ in LiF has been estimated to be B Ӎ 0.9 ϫ 10 −5 g cm −1 s −1 . This value is in accordance with the corresponding coefficient for dislocations in ionic lattices.

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“…The width of the sample l x is much greater than its thickness l y   0.3 mm. Besides, let us estimate the maximal contribution from the longitudinal magnetostriction that is usually taken into account [19]. Magnetostrictive strain can be neglected because: i) it has opposite sign (so it cannot help us elongate our sample); ii) its magnitude does not exceed 10 4 .…”

Section: Nonequilibrium Kinetics Of Electron-phonon Subsystemmentioning

confidence: 99%

“…The measurement precision was about  5·10 5 cm. Activation parameters and internal stress level were determined by means of differential methods that are described in early works (see, for example, [2,[9][10][11][12][13][14][15][16][17][18][19]). The electron microscope investigations of nickel defect structure before and after magnetic field influence were carried out.…”

Section: Study Of Creep Characteristics and Activation Parameters Of mentioning

confidence: 99%

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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Dislocation dragging by electrons in metals

Cited by 71 publications

References 44 publications

Quantum creep of β–Sn in the normal and superconducting states. Influence of the NS transition on work hardening

Quantum creep of β–Sn in the normal and superconducting states. Influence of the NS transition on work hardening

Mechanism of electromagnetic emission in plastically deformed ionic crystals

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

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