Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals
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...
Gespeichert in:
| Veröffentlicht in: | Металлофизика и новейшие технологии |
|---|---|
| Datum: | 2016 |
| Hauptverfasser: | , , , , , |
| Format: | Artikel |
| Sprache: | Englisch |
| Veröffentlicht: |
Інститут металофізики ім. Г.В. Курдюмова НАН України
2016
|
| Schlagworte: | |
| Online Zugang: | https://nasplib.isofts.kiev.ua/handle/123456789/112604 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals / V. I. Karas, E. V. Karasyova, A. V. Mats, V. I. Sokolenko, A. M. Vlasenko, and V. E. Zakharov // Металлофизика и новейшие технологии. — 2016. — Т. 38, № 8. — С. 1027-1055. — Бібліогр.: 36 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859468962744500224 |
|---|---|
| author | Karas, V.I. Karasyova, E.V. Mats, A.V. Sokolenko, V.I. Vlasenko, A.M. Zakharov, V.E. |
| author_facet | Karas, V.I. Karasyova, E.V. Mats, A.V. Sokolenko, V.I. Vlasenko, A.M. Zakharov, V.E. |
| citation_txt | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals / V. I. Karas, E. V. Karasyova, A. V. Mats, V. I. Sokolenko, A. M. Vlasenko, and V. E. Zakharov // Металлофизика и новейшие технологии. — 2016. — Т. 38, № 8. — С. 1027-1055. — Бібліогр.: 36 назв. — англ. |
| collection | DSpace DC |
| container_title | Металлофизика и новейшие технологии |
| description | 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.
Наведено результати досліджень характеристик плазучости та активаційних параметрів пластичної течії полікристалічного ніклю (99,996% чистоти) за постійної температури у 77 К. Досліджувався вплив нестаціонарного магнетного поля напруженістю у 500 Е (гармонічні (50 Гц) та однополярні імпульси тієї ж частоти) на параметри плазучости ніклю. Експериментальні дослідження з впливу нестаціонарного магнетного поля змінного та сталого знаку за постійної температури проводилися, щоб оцінити внесок у рухливість дислокацій від взаємодії дислокацій з рухливими межами домен, а також від теплових ефектів, пов’язаних з індукційним електричним полем. Пропонований модель електропластичного ефекту (ЕПЕ) передбачає наступний механізм знеміцнення під дією електричного 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. Короткохвильові фонони, завдяки великому ґрадієнту напруги, ефективно відкріплюють дислокації від стопорів. Результати експериментів якісно збігаються з даними числових розрахунків.
Представлены результаты исследования характеристик ползучести и активационных параметров пластического течения поликристаллического никеля (99,996% чистоты) при температуре 77 К. Было изучено влияние нестационарного магнитного поля напряжённостью 500 Э (гармонические (50 Гц) и монополярные импульсы той же частоты) на параметры ползучести никеля. Экспериментальные исследования влияния нестационарного магнитного поля постоянного и переменного знака при постоянной температуре проводились с целью оценить вклад в подвижность дислокаций от взаимодействия дислокаций с подвижными доменными границами, а также от тепловых эффектов, связанных с индукционным электрическим полем. Предлагаемая модель электропластического эффекта (ЭПЭ) подразумевает следующий механизм разупрочнения под действием электрического поля. Электрическое поле передаёт энергию подсистеме электронов проводимости, делая её термодинамически неравновесной. Неравновесные электроны, взаимодействуя с акустическими фононами, передают энергию преимущественно коротковолновой части фононного спектра. Коротковолновые фононы благодаря большому пространственному градиенту напряжения эффективно открепляют дислокации от стопоров. Экспериментальные результаты качественно совпадают с данными численных расчётов.
|
| first_indexed | 2025-11-24T06:11:23Z |
| format | Article |
| fulltext |
1027
ФИЗИКА ПРОЧНОСТИ И ПЛАСТИЧНОСТИ
PACS numbers:61.72.Ff, 61.72.Hh,62.20.Hg,63.20.kd,63.20.kp,75.80.+q, 83.60.Np
Influence of Alternating Magnetic Field
on Physical and Mechanical Properties of Crystals
V. I. Karas*,**, E. V. Karasyova*, A. V. Mats*, V. I. Sokolenko*,
A. M. Vlasenko*, and V. E. Zakharov***,****
*National Science Center ‘Kharkiv Institute of Physics and Technology’,
N.A.S. of Ukraine,
1 Akademichna Str.,
61108 Kharkiv, Ukraine
**V. N. Karazin Kharkiv National University,
4 Svobody Sq.,
61022 Kharkiv, Ukraine
***P. N. Lebedev Physical Institute of the Russian Academy of Sciences,
53 Leninskiy Prosp.,
119991 Moscow, Russia
****L. D. Landau Institute for Theoretical Physics of the Russian Academy of Sciences,
1-A Academician Semenov Ave.,
142432 Moscow Region, Chernogolovka, Russia
The results of the investigation of creep characteristics and activation pa-
rameters 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 delib-
erately conducted experimental investigations of the influence of nonsta-
tionary magnetic field of alternating and constant sign at constant tempera-
ture 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 pro-
posed model of electroplastic effect (EPE) suggests the following mechanism
of weakening under the action of electric field. Electric field gives energy to
Corresponding author: Vyacheslav Ignatovych Karas
E-mail: karas@kipt.kharkov.ua
Please cite this article as: V. I. Karas, E. V. Karasyova, A. V. Mats, V. I. Sokolenko,
A. M. Vlasenko, and V. E. Zakharov, Influence of Alternating Magnetic Field on
Physical and Mechanical Properties of Crystals, Metallofiz. Noveishie Tekhnol., 38,
No. 8: 1027—1055 (2016), DOI: 10.15407/mfint.38.08.1027.
Металлофиз. новейшие технол. / Metallofiz. Noveishie Tekhnol.
2016, т. 38, № 8, сс. 1027—1055 / DOI: 10.15407/mfint.38.08.1027
Оттиски доступны непосредственно от издателя
Фотокопирование разрешено только
в соответствии с лицензией
2016 ИМФ (Институт металлофизики
им. Г. В. Курдюмова НАН Украины)
Напечатано в Украине.
1028 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
conductivity electron subsystem, making it thermodynamically nonequilib-
rium. 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 магнитного поля напряжённостью 500 Э (гармонические
(50 Гц) и монополярные импульсы той же частоты) на параметры ползу-
чести никеля. Экспериментальные исследования влияния нестационар-
ного магнитного поля постоянного и переменного знака при постоянной
температуре проводились с целью оценить вклад в подвижность дислока-
ций от взаимодействия дислокаций с подвижными доменными граница-
ми, а также от тепловых эффектов, связанных с индукционным электри-
ческим полем. Предлагаемая модель электропластического эффекта
(ЭПЭ) подразумевает следующий механизм разупрочнения под действием
электрического поля. Электрическое поле передаёт энергию подсистеме
электронов проводимости, делая её термодинамически неравновесной.
Неравновесные электроны, взаимодействуя с акустическими фононами,
передают энергию преимущественно коротковолновой части фононного
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1029
спектра. Коротковолновые фононы благодаря большому пространствен-
ному градиенту напряжения эффективно открепляют дислокации от сто-
поров. Экспериментальные результаты качественно совпадают с данными
численных расчётов.
Ключевые слова: магнитопластический эффект, переменное магнитное
поле, подвижность дислокаций, скорость ползучести, ферромагнитный
кристалл, неравновесная электронная и фононная подсистемы.
(Received June 13, 2016)
1. INTRODUCTION
The discovery of magnetoplastic effect (MPE) [1, 2] and electroplastic
effect (EPE) [3, 4] has stimulated broad study of the influence of con-
stant and nonstationary magnetic fields on the structure and mechani-
cal properties of ferromagnetics and antiferromagnetics [2]. MPE was
being studied under the conditions of active strain and creep. The ob-
served effects were connected with changes in dislocations dynamics
during their interaction with spin subsystem and with the characteris-
tics of the barriers.
In the sixtieth of the XX century, a phenomenon of abrupt decrease
of plastic deformation resistance of metals in case of excitation of their
conductivity electron subsystem by irradiation or conduction of elec-
tron current of high density, j 108—109
A/m2, was discovered. This
phenomenon has been called electroplastic effect (EPE) [3]. This effect
is already being applied in industry in the processes of drawing and
rolling of metallic products [4—8].
2. STUDY OF CREEP CHARACTERISTICS AND ACTIVATION
PARAMETERS OF NICKEL IN EXTERNAL NONSTATIONARY
MAGNETIC FIELD
In the given paragraph, we shall present the results of the investiga-
tion of the creep characteristics and activation parameters of the poly-
crystalline nickel plastic flow at the temperature of 77 K. The influ-
ence of nonstationary magnetic field with strength of 500 Oe (harmon-
ic (50 Hz) and detected (monopolar pulses of the same frequency)) upon
the nickel creep characteristics was studied. Their connection with the
material structural state was also analysed. We have deliberately con-
ducted experimental researches of the influence of nonstationary
magnetic field of alternating and constant sign at constant tempera-
ture in order to estimate the contribution to the dislocations mobility
from the interaction of dislocations with the mobile domain boundaries
and from the heat effects connected with the induction electric field.
1030 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
The object of research was the polycrystalline nickel of 99.99% pu-
rity, which had been annealed at the temperature of 900C during 2
hours. The experiments were conducted at the transient creep stage in
the mode of step loading in the liquid nitrogen environment at the
temperature of 77 K on the test machine with grips and pulls made of
nonmagnetic material. 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—19]). The electron microscope investigations of
nickel defect structure before and after magnetic field influence were
carried out.
In order to study the magnetic field influence, the test specimen was
placed inside a solenoid where the longitudinal magnetic field with the
strength of 500 Oе was created.
In order to determine the peculiarities of the structure that had
formed in the process of creep in the stress range of 0.5 В, the acti-
vation parameters were investigated that allows us to make some con-
clusions about the type of barriers and the mechanisms that govern the
nickel plastic flow during the creep process at 77 K.
Experimental researches showed that activation volume and activa-
tion energy calculated according to the thermoactivated plastic flow
theory are equal to 0.7210
23
cm
3
and 0.14 еV correspondingly and de-
crease with the increase of stress. It means that the dislocations glide
is controlled by the defects that emerge during the process of plastic
flow. The whole magnitude of the activation energy necessary for the
overcoming of obstacles is equal to 0.22 еV and does not depend on
temperature. There are different obstacles that can control the low-
temperature creep of nickel, which means that they have activation
parameters close to those obtained. These are dopants, point strain de-
fects and forest dislocations.
Though it was experimentally confirmed that the activation volume
does not depend on stress, the dopants do not control the creep at 77 K.
Though the concentration of point defects and dislocations increases
with the increase of strain, activation volume has to decrease that is in
accordance with the experiment.
Therefore, the performed experimental investigations and esti-
mates allow us to make a conclusion that, taking into account the dis-
locations density in the region of dislocations bunches, forest disloca-
tions and point defects (mostly interstitial atoms at the initial stages
of plastic strain) are the barriers that control nickel low-temperature
plastic flow process.
In case of the action of the magnetic field of alternating sign, the
main mechanism of the nickel plastic flow at 77 K is the mechanism of
thermo-activated overcoming of the obstacles, enumerated above, by
dislocations. In order to change the plastic flow mechanism, we used
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1031
the action of the constant-sign magnetic field, the strength of which
changed only its magnitude.
The electron microscope investigations show that the annealed nick-
el has strongly equilibrium structure as a result of recrystallization
during annealing, which is indicated by even long traces of the grain
boundaries. Dislocations density does not exceed 5108
cm
2. Creep at
77 K results in spatially nonuniform developing of the material flow,
strong orientation dependence of the defects formation on the grain
orientation relative to the direction of external stress action. For ex-
ample, in some grains, a cell structure with crumbly boundaries and
bunch size of 0.5—0.8 m is observed. Average dislocations’ density
inside the bunches equals to 21010
cm
2
and to 91010
cm
2
in the
bunch boundaries. While in the adjacent grain, one can see strong dis-
location bunches of the density of 81010
cm
2.
In the same time, there are grains where only the initial stages of
plastic flow with dislocation glide along the boundaries and formation
in the triple junctions of bunches with dislocation density of 51010
cm
2
occurred.
The main test series with superimposing the magnetic field upon the
plastic strain process was carried out according to the following sche-
ma. After applying of stress and reaching the strain rate of 510
6
s
1,
the magnetic field was turned on and the creep was being detected dur-
ing 180 s. After turning off the field, the creep lasted 180 s more.
Then, the sample was additionally loaded again. The investigations
were conducted at the transient creep stage at the stress of 0.5В.
The creep strain obtained during 180 s after turning on the field was
considered to be the magnitude of the weakening effect. Figures 1—3
demonstrate the dependence of strain on time for 2 modes of turning
Fig. 1. Influence of nonstationary magnetic field of 500 Oе on the creep of
nickel at 77 K and the stress of 0.3В for different types of magnetic field
pulses with 0.005 s: periodic monopolar pulses (a) and harmonic pulses (b).
1032 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
on the nonstationary magnetic field with the increasing time of 0.005 s
for periodic monopolar pulses (a) and of 0.005 s for harmonic pulses
(b).
Experiments shown that turning on of the stationary magnetic field
of the strength of 500 Oe during the creep of nickel specimens leads to
the increase of strain, and turning off the magnetic field is also accom-
panied by the growth of strain. Weakening takes place with the change
of magnetic field from 0 to 500 Oe and conversely. Figure 3 shows typ-
Fig. 2. Influence of nonstationary magnetic field 500 Oе on the creep of nickel
at 77 K and the stress of 0.3В for different types of magnetic field pulses
with 0.005 s: periodic monopolar pulses (a) and harmonic pulses (b).
Fig. 3. Influence of nonstationary magnetic field of 500 Oе on the creep of
nickel at 77 K and the stress of 0.5В for different types of magnetic field
pulses with 0.005 s: periodic monopolar pulses (a) and harmonic pulses (b).
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1033
ical nickel creep curves change as a result of turning on and off the
nonstationary magnetic field of the strength of 500 Oe with different
growth time under the strength of 0.5В. One can see that after
turning on and off the magnetic field with different growth time the
form of the creep curves changes essentially: the lesser the growth
time the greater the strain rate jump for each investigated value of
strength. Let us mention that the case (a) corresponds to short mono-
polar pulses.
Figure 4 illustrates the manifestation of the nickel weakening effect
at different modes of the magnetic field action.
Figure 4 also shows that weakening under the action of monopolar
Fig. 4. Dependence of the polycrystalline nickel weakening magnitude at 77 K
in stationary magnetic field with the growth time of 1 s (1), periodic monopo-
lar pulses (2) and harmonic magnetic field (3) of the strength of 500 Oe upon
strain degree.
a
b
Fig. 5. Dislocation structure of nickel after the 9% strain under the condi-
tions of stage creep at T 77 K and superposition of nonstationary magnetic
field of 500 Oe with different field growth time : 60 s (a) (single pulse),
0.005 s (periodic monopolar pulses) (b).
1034 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
pluses and stationary field with the growth time of 1 s practically coin-
cides in a wide range of creep strain stages. In case of harmonic pulses,
the weakening grows essentially with the increase of strain.
Electron microscope investigation showed that nonstationary mag-
netic field influences the material structure the stronger the lesser the
field growth time is (see Fig. 5). The body of bunches is cleaned from
dislocations and they concentrate only on the boundaries (Fig. 5, b).
Dislocation density on the boundaries greatly exceeds 1011
cm
2
and
cannot be distinguished by the methods of electron microscopy and
near the grain boundaries strong dislocation bunches are formed (see
Fig. 5, b).
3. THEORETICAL INVESTIGATION OF WEAKENING OF NICKEL
AT CREEP IN NONSTATIONARY MAGNETIC FIELD
3.1. About the Influence of Phonons on Dislocations
Plastic deformation of crystals under the action of external loads in
most cases is accomplished by dislocation glide. The main equation de-
scribing the kinetics of the process of the plastic deformation–the
Orovan modified equation (see, for example, [20]):
* *( ), ,
d d d i
bl (1)
where d is the strain rate, |b|–the Burger’s vector, l–the mean dis-
tance between stoppers, d–the mobile dislocations density, d(*)–
the frequency of the stoppers overcoming by dislocations, *–the ef-
fective shear stress, i–the internal shearing stress in the glide plane.
For the case of thermodynamic equilibrium, the expression for
d(*, T) has the form of
*
* 0 ( )
( , ) exp ,d d
B
H
T
k T
(2)
where kB is the Boltzmann constant and T is the temperature.
The explicit form of the H(*) function depends on the potential bar-
rier model. For the consideration of a more general case, i.e. when elec-
tron and phonon subsystems can be, generally speaking, in the state of
nonequilibrium, the Landau—Hoffman model will be used [21]. The po-
tential pit has parabolic form
2
cr
cr
cr 0
, ,
( )
0, ,
.
x x x
U x
x x
x U
(3)
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1035
The displacement of the dislocation segment of length L under the
stress will be described in the approximation of the elastic string vi-
brations (Granato—Lücke model [22]):
2 2
2 2
( ).
u u u
M B C b f t
ty y
(4)
Here, u(y, t) is the displacement of the dislocation line at the point y in
the direction x,
2
2
b
M
is the effective mass of the length unit, ρ is
the material density, В is the coefficient of the dynamic friction force
per unit of length,
2
2
Gb
C –the linear tension of the string, G is the
shear modulus, f(t) is the force of the random pushes that are exerted
by crystal upon the unit of dislocation length.
Boundary conditions are:
2
(0, ) (0, ), ( , ) ( , ), .u t ku t u L t ku L t k
C
(5)
The equation (4) is linear, so its solution can be written as a sum
st osc
( , ) ( ) ( , ),u y t u y u y t
where ust(y) is the static deflection, caused by external stress , and
uosc(y, t) are the oscillations under the action of a random force
st osc
1
( )
( ) , ( , ) ( ) sin( ) cos( ) ,
2 2
N
n
n n n
n
qby L y bL
u y u y t Q t q y q y
C Ck k
2 2
ctg( ) .
2
n
n
n
q k
q y
q k
(6)
The quantity of Qn(t) satisfies the following equation
2 2 2( ) ( ) ( ) ( ), .n n n n n n n
C
MQ t BQ t M Q t f t q
M
(7)
Let us consider a ‘fixing point’ at y 0. Let the segment lengths on
both sides of it be equal to L. Then, the total deflection at the ‘fixing
point’ is equal to
st osc st osc
(0, ) 2 ( ) 2 ( , ) ( ) ( , ).u t u y u y t u y u y t (8)
The case of a random force was considered in the work [22]. We shall
now provide some of the calculations for the reference purpose. If, at
1036 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
some time moment, a random event occurs such that cr(0, )u t u ,
then, the condition of obstacle overcoming in the direction on the load-
ing action will be satisfied. Let fn(t) be a stationary Gauss process.
Since the equation (7) is linear, Qn(t) and correspondingly (0, )u t is
also stationary Gauss process for which the mean number of exceeding
a particular quantity cru per unit of time is equal to
2
cr1 (0)
exp ,
2 (0) 2 (0)
u
(9)
2 2
2 2
1 1
( ) 2 ( ) ( ) 2 ( ),
n n
n n
n n
n n
q q
Q t Q t
k k
(10)
cr
cr cr cr cr
cr
1 , ,
CkxbL
u x x
Ck bL
(11)
where () is the random process (0, )u t correlation function ex-
pressed by means of random process Qn(t) correlation function ();
(0) is the second derivative with respect to at 0. For the Fourier
components (Qn) of Qn(t), we can write
2( ) ( ) ,i
n
Q e d
(12)
where the definition of the quantity
2( )nQ is given by the relation
2
( ) ( ) ( ) ( ).
n n n
Q Q Q (13)
Each harmonic can be formally considered as an independent vibra-
tor with friction and frequency n:
2 ,
n
mQ Q m Q F (14)
where m is the proportionality coefficient between the generalized
momentum and velocity ,Q is the friction coefficient, F is the ran-
dom force [22]
2
2
2
, , , 1 .
2 2 2
n n n n
n n
L L L q
m M B F f
kL k
(15)
Therefore, for the Fourier component, we obtain the following for-
mula:
2
2
2 2 2 2 2 2
( )
( ) .
( )
n
n
F
Q
m
(16)
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1037
Random force spectral density can be found from the expression [23]
2 1
( ) ( ) .
2
F N
(17)
Hence, to estimate the force exerted by phonons upon dislocations,
one must first find the phonon distribution function N() [24—29].
3.2. Nonequilibrium Kinetics of Electron—Phonon Subsystem
Though we investigate the behaviour of a sample in harmonic and non-
stationary magnetic field, it is important to estimate the influence of
eddy electric field, induced by nonstationary magnetic field, upon the
change of the mechanical properties of the sample [30]. Using the
Maxwell equations, we can estimate the characteristic magnitude of
the electric field
0
0
0
41
rot ( ), ( ),
| sin( / 2 ) |, ( ( ), ),
x z z
z z
H
E l H H
c t c
H H t H t t
E H
(18)
where is the magnetic field growth time, lx is the sample width, lx 3
mm. The width of the sample lx is much greater than its thickness ly
0.3 mm.
Besides, let us estimate the maximal contribution from the longitu-
dinal magnetostriction that is usually taken into account [19]. Magne-
tostrictive 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.
For simplicity, while solving the set of kinetic equations for elec-
trons and acoustic phonons, we consider spatially uniform electric
field as well as distribution functions of electrons and phonons. Elec-
tron distribution function becomes isotropic as a result of electron-
dopant collisions [24, 25]. In this case, we can neglect the umklapp pro-
cesses. In case of relatively small electric fields, the contribution from
electron—phonon collisions greatly exceeds the contribution from elec-
tron—electron interaction, and therefore hereinafter, at small time in-
tervals, the electron—electron collisions will not be taken into account
[23—25].
For the phonon distribution function, we also take into account the
finite lifetime of phonons (second term in (19)) in our system
0
pe
( ) ( ) ( )
,
b
N N N
I
t
q q q
(19)
1038 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
where Ipe is the phonon—electron collision integral [24—27],
1
0 ( ) [exp( / ) 1]BN k Tq is the thermodynamically equilibrium
phonon distribution function–Bose—Einstein function at T0, T0 77 K
is the temperature of liquid nitrogen, ( ) ,q sq q is the phonon mo-
mentum, s is the transverse sound velocity, b (s/sN2)
2ly/2s, sN2
8.67104
cm/s is the sound velocity in liquid nitrogen.
In the considered case, the frequency of electron-phonon collisions is
much less than the frequency of the collisions of electrons with de-
fects. Collisions with defects and dopants occur very often, at time in-
tervals small compared to the characteristic phonon—electron interac-
tion time. That is why the anisotropic additive can be considered sta-
tionary and spatially uniform. As a result, we obtain the final set of
two equations for isotropic distribution functions of electrons and
acoustic phonons [24, 25, 27—29], which is to be solved without Tailor
expansion of electron distribution function
3
2
1
2
1
4
f f
t
5
22
0
1 1
( ) ( ) ( ) ( ) 1 ( )
8
ph ph ph ph ph phd f N f f N
5
22
0
1 1
( )[ ( ) 1] ( )( ( ) ( )) ,
8
ph ph ph ph ph phd f N f f N (20)
0
( ) 1
( ( ) ( )) ( ) ( )(1 ( ))
2
ph ph ph
N q
d f f N f f
t
0
( ) ( )
.
b
N q N q
(21)
Here, the following designations are used:
2 22
0
, , , , ,
2 6 2
ep ph
ph
B e ed B e B e B eB e
e Ems p
p
k T m k T k T k Tmk T
3
7
0 3 2
0 1
(2 )
, 3.446 10 s.
ep
ep A
t
t
m s
Integration limits, which are obtained with respect to energy con-
servation law, are correspondingly equal to
min 4( ), , min 4( ), ,
D Dph ph
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1039
2
0
.
16 2
ph ph
(22)
Distribution functions of electrons, f(), and phonons, N(q), are di-
mensionless quantities, which satisfy the following normalizing condi-
tions:
3
1
2
2
2 2
0
1 2
( ) ,
2
m
f d n
(23)
where n is the electron concentration in the valence band (for metals
also conduction band, which is only partially filled);
2
2 3
0
1 1
( ) ,
2
Dq
q N q dq
(24)
where qD is the momentum of Debye phonon, which is defined by the
expression
2.Dq
a
(25)
All the quantities are taken for nickel: s 2.96105
cm/s is the trans-
versal sound velocity, n 2.51022
cm
3
is the electron concentration in
the conduction band, a 3.510
8
cm is the lattice parameter,
1
s
0.333106
S/cm is the specific residual resistance.
Thermodynamically equilibrium electron energy distribution func-
tion is the Fermi—Dirac function:
1
0
( ) exp 1 ,F
B e
f
k T
(26)
where F 510
19
J is the Fermi energy for nickel, Te is the initial elec-
tron temperature 77 K.
4. COMPARISON OF DIFFERENT THEORETICAL MODELS
WITH EXPERIMENTAL DATA
Electroplastic effect, i.e. the phenomenon of weakening of metals dur-
ing plastic strain while conducting high-density electric pulses, has
been known more than 50 years already. This phenomenon is widely
used in manufacturing of different metallic products. Though the in-
fluence of different parameters upon the magnitude of this effect is
experimentally studied, there exists no sole quantitative theory yet.
In this section, we compare our approach with those most widely
1040 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
used for explanation of the electroplastic effect. In the first subsec-
tion, we review the works of Hans Conrad and co-authors [31]. They
approach to the explanation of EPE from the point of view of the elec-
tron wind theory, i.e. the direct action of drift conductivity electrons
upon the dislocation motion. Experiments are conducted, as a rule, at
constant strain rate. Based on the measured mechanical loading drop
that accompanied the conduction of current pulse, the authors deter-
mine the electron drag coefficient and compare it to that predicted
theoretically.
The second subsection deals with the Michel Molotskii’s theory,
which is presented in his articles [32—34]. In his earlier works, Mol-
otskii considered the influence of magnetic field on the interaction of
dislocations with paramagnetic dopants-stoppers. From the point of
view of this model, electroplastic effect emerges as a result of the in-
fluence of the self-magnetic field generated by the current. The author
has made some mathematical inaccuracies that will also be considered
and corrected as far as possible.
Third subsection is about the approach of Bilyk et al. [35]. Their con-
clusions contradict the prior works, in particular those reviewed in
this report. Therefore, the authors think that it is thermal expansion
due to Joule heating, which plays the key role. Direct influence of cur-
rent upon dislocations, if it exists, is considered by the authors to be
secondary effect.
4.1. Influence of the Electric Current Density upon the Plasticization
of Metals
The influence of high-density (105
А/cm2) current pulses upon the
plastic flow stress of polycrystalline metals at axial strain was re-
searched in the article [31]. Pulse duration was 60 s. Temperature
300 K. The observed increase in dislocation mobility was explained by
the action of drift electrons.
Experiment. At first, the samples were deformed at constant strain
rate of 1.710
4
s
1
until the degree of strain that is slightly lower than
it was desired. Then, the elasticity modulus of the test machine was
measured. After that, the plastic strain of the sample went on until the
necessary strain degree while two current pulses within the interval of
10 s were passed through the sample. Loading drops f were observed.
Then, the sample was unloaded to the level of long-range internal
stress, and for current, pulses within the interval of 60 s were passed
through it. It was accompanied by the stress drops e. Then, the rou-
tine was repeated for the higher degree of strain. e is the contribu-
tion to the loading drop from the elastic strain caused by such ‘side’
effects of current as pinch effect, skin effect, magnetostriction and
thermal expansion due to Joule heating. So, the difference p f
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1041
e is the contribution from the plastic strain.
The dependence of loading drop p on strain degree was deter-
mined. For body centred cubic (b.c.c.) metals, the dependence is de-
scendant. For face centred cubic (f.c.c.) metals, the dependence was
absent. For b.c.c. nickel and titan, the dependence was nonmonotonic.
The flow stress after passing of the current pulse returned to its previ-
ous value that testifies that no significant change in dislocation struc-
ture of the sample occurred as a result of current pulse passing.
The behaviour of metals and alloys under the influence of high-
density current pulses and stationary electric field was studied in the
work [31]. In the theoretical part, special attention was payed to the
consideration of dislocation motion under the influence of electron
wind.
Pulse current with the current density of 103—106
А/cm2
and pulse
duration of 100 s was applied. The increase of strain rate at low homo-
logical temperatures under the action of pulse current was observed.
The fatigue life increased. In addition, the recrystallization rate in-
creased.
It was ascertained that conducting of current pulses of density of
the order of 105
А/cm2
and duration under 100 s increases plastic
strain rate.
The Influence of Pulse Current. Direct dependence of the effect mag-
nitude on the prior strain rate was revealed. The investigations were
conducted with niobium at the temperature of 300 K in the strain rate
range from 1.710
5
to 8.410
4
s
1.
Conducting of current pulses of the density of 1.3104
A/cm2
during
rotational bending of Ni and Cu samples caused the 1.2—3 times in-
crease of their durability, which was manifested by the increase of the
number of loading cycles needed for microcrack formation, and also by
the decrease of the crack growth rate. Influence of the pulse current
also revealed itself by increase of the slip band density.
Conduction of 105
A/cm2
density, 100 s duration and 2 s period
current pulses through copper during annealing increased the recovery
and recrystallization rate and decreased the grain growth rate. Recrys-
tallization of more fine grains took place. The magnitude of recrystal-
lization rate increase decreased with the increase of the time of prior
cold working. Pulse current accelerated the recrystallization kinetics
at the cost of pre-exponential factor without essentially influencing
the activation energy. Maximal temperature rise due to Joule heating
did not exceed 2 K. Similar effects were observed also at annealing of
high purity (99.996%) and commercial purity (99.8%) Al, and inter-
metallic compound Ni3Al containing boron. The pulse current influ-
ence upon recrystallization is prescribed to its influence upon the for-
mation and merging of subgrains.
Conduction of current pulses (density 105
A/cm2, duration 60—95 s
1042 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
and frequency 4.2—8.7 Hz) through the samples of two amorphous
iron-based alloys (Fe75Si10B15 and Fe79Si7B14) caused the precipita-
tion of -iron at temperatures, which were more than 150 K less than
those at which iron crystallization without electric current is ob-
served. Possible reason–enhanced diffusion rate (electromigration).
Sintering of aluminium powder under the conditions of conduction
of 2.7105
A/cm2, 10 s duration and 1 pulse per 30 s frequency electric
current pulses caused 30% decrease of porosity.
Direct current influence was discussed in the work [31].
Adding of stationary kV/cm electric field caused slowing down re-
crystallization and recovery processes in Al and Cu that underwent
cold working. Grain growth and void formation during superplastic
strain of Al7475 alloy was also decelerated. Quench ageing, bainite
formation and steel tempering processes were also slowed.
The contrary was observed in case of Ni3Al alloy – acceleration of
recrystallization and recovery. Ascending dependence of electroplastic
strain magnitude on strain rate was observed.
Direct 6.5102
А/cm2
density current has slightly increased the tem-
pering if 0.9С instrumental steel. The effects of alternating 60 Hz and
pulse current were yet less. Pulses of current (j 2.3105
А/cm2, 10 s
duration, 1 pulse per 30 s) during the sintering of cold pressed alumin-
ium powder samples caused the 30% porosity decrease.
Applying of stationary electric field Е 2 kV/cm to the sample of
Al7475 alloy that was undergoing superplastic strain at the tempera-
ture of 520С caused such effects: а) flow stress drop; b) deformation
strengthening rate decrease; c) slight increase of deformation
strengthening exponent; d) fourfold decrease of void volume fraction
in the 1.2 mm thick sample. The mechanism of those effects was not
entirely clear, because the magnitude of electric field in the bulk of
sample has to be zero.
Adding of 2.4—8 kV/cm electric field during isochronal annealing of
Cu and Al resulted in the increase of recovery and recrystallization
temperatures, despite of the fact that the field damped those phenom-
ena (contrariwise to the pulse current effect). In a sufficient stress-
field strength range, the effect has not been revealed. In addition, we
have no dependence on dielectric constant of the medium containing
sample. The above-mentioned effects took place not only at the surface
but also in the bulk of the sample.
10 kV/cm electric field slowed quench aging of 99.9% iron.
1—2 kV/cm electric field applied at the quench strengthening and
tempering of steel 4 340, as well as instrumental steel 02(0.9С), caused
the following effects: а) growth of austenisation rate; b) quenching en-
hancement; c) slight decrease of tempering rate. In case of tempering
in a mineral oil, the electric field had such influence on microstruc-
ture: а) slight refinement of austenite grains; b) decrease of upper
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1043
bainite fraction; c) decrease of microtwins’ density in martensite.
Above-mentioned effects were observed in the bulk of 2—3 mm thick
sample as well as at its surface.
Skin effect, pinch effect and magnetostriction were taken into ac-
count. In all cases, the skin depth has exceeded the samples radii,
which were equal to 0.17—0.25 mm several times. So, the current was
distributed practically uniformly over the sample cross-section.
The contribution of pinch effect to the load drop was 0.25—0.77 MPa
that is small compared to total load drop.
The contribution of magnetostriction was also small.
The heating of the sample was measured by means of thermocouple.
Authors [31] consider Joule heating to be the most important of the
current influence side effects. It is Joule heating that makes crucial
contribution to the magnitude of reversible strain. Temperature raise
under the condition of adiabatic heating ranged from 5 (copper) to 160
(titanium) K for the 5500 A/mm2
density of current. The magnitude of
loading drop due to thermal expansion turned out to be only slightly
less than the measured e.
Alongside with side effects electric current also exerted direct in-
fluence on material plastic flow. The magnitude of the additional
force, caused by this effect, is compared to the magnitude of ‘electron
wind’ force, calculated according to three different models. A match
by the order of magnitude with Roshchupkin’s model was obtained.
Other two models predict the magnitude two orders less than observed.
Authors think that the effect consists of the ‘electron wind’ force,
which is proportional to the current density, and of the effect of unclear
nature, the contribution of which is proportional to the current density
squared. Strain rate change is described by the following formula
2 exp( ),
j
a
j j
(27)
where a and j are strain rates before and during conduction of cur-
rent pulses of density j correspondingly, and are the material pa-
rameters.
Electron wind force per unit of dislocation length for Al and Cu has
the following form:
Few Kewj, where Kew 510
8
(dyne/cm)/(А/cm2). (28)
Electron drag coefficient can contain phonon component, which
emerges due to the interaction of drift electrons with the phonons. Be-
cause of electron—phonon collisions, a nonstationary phonon flux in
the direction of current can emerge. Force excreted by phonon flux up-
on dislocation, being added to the electron drag force, can assist dislo-
cations in overcoming obstacles.
1044 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
Other possibility is connected with the influence of electric current
upon the stacking fault. Its decrease would cause the increase of mobile
dislocations velocity.
Except electron wind, drift electrons can also influence thermoacti-
vation parameters. This effect depends on the current density squared.
4.2. Influence of the Electric Current Density on the Plasticization
of Nonferromagnetic Materials
Michel Molotskii in his works [32—34] proposes the following model of
the influence of magnetic field upon the plastic properties of the mate-
rial. Electroplastic effect, according to Molotskii, is a particular mani-
festation of magnetoplastic effect, when the magnetic field is created
by the electric current. That is why Molotskii considers only the influ-
ence of the magnetic field.
According to his model, magnetic field changes the mutual orienta-
tion of spins of the dislocation core and paramagnetic dopant. Anti-
parallel spin orientation is characterized by the strongest bond. In the
states with different spin orientations, the binding energy is essential-
ly less that eases the depinning of dislocations from the dopants.
Without the magnetic field, each of the four possible mutual spin
orientations is realized with the equal probability. Imposing of the
magnetic field causes the increase of the number of weakly coupled
radical pairs that is equivalent to the decrease of the dopant concentra-
tion. Molotskii finds the dependence of the population of certain spin
sates on the magnitude of the magnetic field.
2
1 2
2
1 21 2
1
1
1 1
21
( ) , ,
4
1 1 1
2
m
ss m
B
m
T T H
H
H H
g TTT T H
T H
(29)
where Т1 and Т2 are the characteristic times of the longitudinal and
transversal spin relaxation, is the average time for the radical pair to
pass the resonance region. Introducing the following designations
1 2
0
2 1 ,
m
T T
H H
1
1
2
2 ,
T
T
we can rewrite this formula in a more compact form
2
2 2
0
( ) 2
1 .
(0)
ss
ss
H H
H H
(30)
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1045
The next step in the given model is to find the connection between
the field magnitude and the dislocation mean free path. In the work
[34], the inverse relationship between dislocation mean free path and
dopant concentration is suggested.
In the article [34], the dislocation mean free path is suggested to be
inversely proportional to the square root of the dopant concentration
(0)
( ) (0) .
( )
ss
ss
l H l
H
(31)
With substituting (30), we obtain
1/2
2
2 2
0
2
( ) (0) 1 .
H
l H l
H H
(32)
From this moment, Molotskii considers the limit case. With respect
to the limit of small field, he obtains the expression for the change of
dislocation mean free path
2
2
0
( )
1 .
(0)
l H H
l H
(33)
Here, the attention should be payed to the disappearing from the for-
mula (32) of the term with (2 4).
In order to determine the dependence of the drop of the deforming
stress at the plastic strain at constant rate on the magnitude of the ap-
plied magnetic field, the author uses the following empiric dependence:
( ) ( ) (0) (0).H l H l (34)
As a result of substitution of the relation found above, Molotskii ob-
tains the following dependence of the stress drop magnitude on the
magnetic field strength
2
2 2
0
( )
.
(0)
H H
H H
(35)
Taking into account the previous remark withholding the H
2-term
in the denominator exceeds the precision of chosen approximation, so
this term should have been discarded as
2
2
0
( )
.
(0)
H H
H
(35а)
Then, Molotskii uses the obtained relation for explanation of the
electroplastic effect, by substituting the value of magnetic field, cre-
1046 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
ated by the electric current of given density.
0 0
1 1
, .
2 2
H jr H j r (36)
He obtains the following relation
2
2 2
0
( )
.
(0)
j j
j j
(37)
The term in the denominator, considering the remarks regarding
(35), should also be discarded. The following should have been obtained
2
2
0
( )
.
(0)
j j
j
(37а)
At the transition from (35) to (37), we have taken into account the
fact that in case of current density that is uniformly distributed over
the cross-section of the conductor, the value H of the magnetic field
strength grows with the distance from the axis of the sample. But, the
parameter H0 is the property of the material and depends neither of the
size of the sample, nor on the coordinates in the bulk of this sample. If
letter ‘r’ in (36) designates the wire radius, then, (37) with respect to
substitution (36) has the meaning of relative stress drop in the circular
layer near the conductor’s surface. If r is the polar radius that varies
from 0 to the radius of the sample, then, j0 is not a constant and does
depend on r.
Considering this, expression (37) should have the following form
2 2
2 2 2
0
1
( , ) 4 ,
1(0)
4
j r
j r
j r H
(38)
Or, introducing the characteristic current density j0,
2
0
2 2
0 0
/( , )
.
(0) / /
r Rj r
r R j j
(39)
Here, a substitution was made
0 0
0
( ) , .
2 2
j Rjr
H r H (40)
It is worth to underline the difference between r and R0 in this sub-
stitution; r is the polar radius that changes from 0 to R0, where R0 is
the radius of the wire. As well as H0, j0 does not depend on the polar ra-
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1047
dius. But, on the contrary to H0, j0 depends on the size of the sample.
Therefore, although we have transited to the notation in terms of
characteristic current density, we should remember that it is the char-
acteristic magnetic field H0 that has crucial physical meaning.
Results predicted by this model are then compared to the experi-
mental data on electroplastics. Experiments give square dependence of
stress drop on current density at small current densities. Molotskii al-
so obtains square dependence, expanding (37) with respect to small j:
2
*
2
0
( ) .
j
j
j
(41)
After substituting j0 from (36), the dependence of the radius of
round wire being deformed has been obtained
2 2
* 0
2
0
1
( ) .
4
j R
j
H
(42)
Here, R0 is the radius of the wire.
Experiments show saturation of the weakening effect magnitude at
large currents. Molotskii obtains saturation by setting in (37) j j0.
In the intermediate range of current densities, a linear dependence
of stress drop on current density was observed. Molotskii shows that
expression (37) in the vicinity of inflection point gives linear depend-
ence:
2 2
0
* 2
0
( ) 1
.
4
j Rj
H
(43)
In order to find the change of stress applied to the whole conductor,
the expression for the relative stress drop should be averaged over the
cross-section of the conductor
2
0
( ) 1 ( , )
.
(0) (0)
j j r
dS
R
(44)
In case of small current density, substitution of (37а) gives
0
2
2
20
02 2
00 0
/( ) 1
/ .
(0) 2/
R
r Rj r
d j j
Rj j
(45)
If we use expression (45) as the author does, then, we obtain
0
2
2
2 20
0 02 2 2
00 0 0
/( )
1 / ln 1 / .
(0) / /
R
r Rj r
d j j j j
Rr R j j
(46)
1048 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
Now let j j0. Expanding the logarithm in a Tailor series, we get the
same result as (45)
2 2 4 2
0 0 0 0
( ) 1 1
1 / / / ... / .
(0) 2 2
j
j j j j j j j j
This result differs from (41) obtained by Molotskii by the factor of 1/2.
Conclusions regarding the linear dependence on current density and
saturation cannot be obtained basing on (37), because it is necessary to
go beyond the domain of applicability of the approximation with re-
spect to which the formula has been obtained.
Let us now consider a general case, when magnetic field can be of
any magnitude. Taking the expression for dislocation mean free path
(32), we obtain
2
2 2
0
( ) 2
1 1 .
(0)
H H
H H
(47)
Let us switch from magnetic field to current density using (40).
Then, the expression for relative stress drop will have the following
form
2 2
0 0
2 2
0 0
1 ( 2) / /( , )
1 .
(0) 1 / /
j j r Rj r
j j r R
(48)
In order to obtain stress drop, we average (48) over the sample cross-
section
0
22 2
0 0
2 2 2
00 0 0 0
1 ( 2) / /( ) 1 ( , )
1 .
(0) (0) 1 / /
R
j j r Rj j r r
dS d
RR j j r R
(49)
As a result, we get
2 2 2
0 0 0
( ) 1
1 / 1 ( 2) / 1 / 1
(0)
j
j j j j j j
2 2
0 0
1 ( 2) / ( 2)(1 / ) /2
ln ,
( 2) 1 ( 2) /
j j j j
2
0 1 2 1 2
( ) 1
1 / 1 ,
(0)
j
j j S S S S
x
20
/ .x j j (50)
Expressions for S1 and S2 and their expansions with respect to small
x are given below
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1049
2
1
0
1 1 1
1 ( 2) 1 1 ,
2x
S x x x x
2 2
0 0
2 3
2
2
1 2 / 1 /
2
ln
2
2 1
j j j j
S
2 2
0
1 1 1 2
.
2 4x
x x x
In case of small current densities,
20 0
( ) 1 1 2
/ 1 , .
(0) 2 2
j
j j j j
(51)
For getting (45) or (46), we need to set 2. However, all critical
remarks do not disprove most part of author’s conclusions. At small
current density, the dependence of relative stress drop on current den-
sity is quadratic. Factor 1/2 in (45), (46), (51) that emerged as a result
of averaging can, however, influence the author’s statement about
quantitative match with some experimental data.
In case of big current density, saturation indeed takes place:
( ) 2
1 , .
(0)
j
j
Author states that predictions of his model qualitatively (and in
some cases even quantitatively) match the experimental data. His
model explains the following regularities of electroplastic effect:
quadratic dependence of the effect magnitude on current density at
small, linear dependence at intermediate and saturation at big current
density. The dependence of the wire diameter is also explained.
4.3. Influence of Thermal Expansion on the Plasticization
of Nonferromagnetic Materials
Deformation of metallic cylinders at conducting through them of high-
density pulse electric current was considered [35]. Viscoplastic model
that takes into account Joule heating and Lorentz force was built. This
model is then applied for explanation of more early experimental re-
sults of other authors concerning electroplastic effect. In cases consid-
ered by authors, current pulses of 60—100 s duration and 105
A/cm2
density were conducted through wires of different metals during their
1050 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
active strain at constant rate of 10
4
s
1. It was shown that, because of
the size of the samples is small compared to skin depth, the current can
be considered uniformly distributed over the sample cross-section.
Pulse duration is small compared to characteristic thermal diffusion
time and much greater than electric field diffusion time that allows
regarding the heating as adiabatic.
It is stated that metal samples behaviour under the action of me-
chanical load and pulse current can be explained by means of well-
known mechanisms of electric current influence, i.e. Joule heating and
Lorentz force, where Lorenz force is secondary factor compared to
Joule heating. Authors think involving of any additional concepts
about interaction of electric current with dislocations to be redundant.
The proposed model presumes the following. At the conduction of
current through the sample, it gets heating that is accompanied by
thermal expansion. It means that between the pulse beginning and the
moment of maximal heating, the sample changes its size at some rate.
If the mentioned process takes place during plastic strain at constant
rate, then, much less loading is needed to maintain this it, or it can be
not required at all. Now, the strain rate of constant magnitude consists
of two parts: plastic and elastic. According to Bilyk’s estimations,
plastic part of strain rate drops approximately on two orders. There-
fore, spasmodic loading drop has to be observed. After pulse conduc-
tion, the sample will begin to cool down, and, consequently, mechanical
stress will have to be increased. Now, elastic constituent of strain is
negative. Plastic part, therefore, is increased. Bilyk et al. [35] presume
the dependences of materials on plastic strain rate to play the key role.
Because of heating occurs much faster than cooling down (during heat-
ing the heat is generated in all the volume of the sample, while the loss
of heat is possible only through surface), the load increase during cool-
ing of the sample is less by magnitude but more extended in time. Ac-
cording to the authors’ estimations, thermal diffusion characteristic
time for different metals samples with the given sizes is 2—4 orders
greater than current pulse duration.
Unger et al. [36] prescribe the main part to expansion. They have
performed their numerical calculations using two models: thermos-
elasto-plastic and thermos-elasto-visco-plastic. The later one takes into
account the dependence of plastic flow parameters on strain rate. Dif-
ference between the results of both models is small. Comparing to ex-
perimental data, the authors got a match with 5% error that can be
partially explained because of the precise experimental pulse shape is
unknown.
Authors suggest [36], that in order to get the complete answer to the
question whether the electric current exerts some additional influence
on plastic strain one needs to perform tests involving deformations of
samples that are heated in nonelectrical ways during the deformation
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1051
process.
Remark: as the authors themselves [36] showed it, characteristic
time of thermal diffusion (and correspondingly the time of heating
through the surface) is of several orders greater than in case of heating
by the current. Therefore, thermal expansion rate will also be smaller.
Therefore, for obtaining precise analogy, we need not only the same
heating magnitude but the corresponding heat rate as well.
Unger et al. [36] achieved the conclusion that direct influence of
current on dislocations, if it exists, is of second order of smallness
compared to the thermal expansion.
So, the effect that had been neglected before has been considered at
completely different angle. Authors have payed attention not only to
the magnitude of thermal expansion but also to the rate of the process,
which makes sense because it is the value of strain rate that is constant
in the experiments.
4.4. Nonequilibrium Electron—Phonon Kinetics Influence
of Electroplasticity of Metals
All quantities are taken for nickel: s 2.96105
cm/s is the transversal
sound velocity, n 2.51022
cm
3
is the concentration of conductivity
electrons, F 510
19
J, lattice constant a 3.510
8
cm, s is specific
residual resistance, measured in experiment s
1
2.27106
S/cm, Te
T0 77 K. Creep rate, observed in tests before turning on of magnetic
field was equal to 2.810
6
s
1, 3.6710
6
s
1, 5.510
6
s
1
for the stress
values of 230 MPa, 270 MPa and 330 MPa correspondingly. These val-
ues can be obtained from the equations (1) and (2) using the following
quantities: b 3.5210
8
cm, l 2.2510
6
cm, d 1109
cm
2, d
0
1.81012
s
1, T 77 K, potential pit depth U 0.22 eV, H(*) U V,
activation volume V 7.2610
24
cm
3. For explanation of the creep rate
jump observed after turning on of magnetic field by heating, tempera-
ture growth should have been of approximately 18 K. For our charac-
teristic electric field, we have the eddy current density of j 3.5105
A/cm2. According to [3, 4], at such current density, EPE takes place
during tens of μs. In those experiments, strain rate was constant and
equal to 10
4
s
1
and the stress drop caused by the conduction of current
pulses was of several %. In our tests, as it can be seen from Figs. 1—3, at
constant stress, the strain rate jump had the magnitude of 10
3
s
1. Ef-
fect of periodic monopolar pulses is much greater than in case of single
pulse with much longer growth time (see Figs. 1—3).
5. CONCLUSION
1. The necessity of kinetic consideration of nonequilibrium dynamics
1052 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
of electron-phonon subsystem of a crystal in a strong electric field was
justified.
2. A method of numerical solution of Boltzmann kinetic equations’ set
for electron and phonon distribution function without expanding elec-
tron distribution function with respect to phonon energy has been pro-
posed.
3. It has been shown that, under the influence of strong electric field,
electron distribution function gets nonequilibrium in the vicinity of
Fermi energy, and due to electron—phonon collisions, substantial ener-
gy transfers to phonon subsystem forming nonequilibrium phonon dis-
tribution function. Based on the Granato—Lücke and Landau—
Hoffmann modified models and using the calculated phonon distribu-
tion function, it was shown that the force exerted by phonons upon dis-
locations is greater than in case of thermodynamically equilibrium
heating of the sample by 12 K observed in experiment.
4. Comparison between results of calculation and experimental data
for nickel at the observed values of experimental parameters has clear-
ly demonstrated that the proposed approach gives results of the same
order of magnitude that the experiment.
5. So, weakening of nickel under the influence of stationary or nonsta-
tionary magnetic field manifests itself at plastic flow that is known to
be caused by the presence and motion of mobile dislocations in crystal.
Therefore, the mechanism of magnetic field influence on plastic prop-
erties of the material are obviously connected with its influence on dy-
namic characteristics of dislocations.
6. We have deliberately conducted experimental research on nonsta-
tionary (constant sign and varying magnitude) magnetic field influ-
ence under the conditions of stationary temperature in order to ex-
clude the contribution to dislocations mobility change an adding of
magnetic field from the interaction of dislocations with the mobile
domain boundaries and from thermal effects. At remagnetization, the
mobile boundaries are known to interact with dislocations by helping
them to overcome local obstacles, causing the increase of mobile dislo-
cations density and creep strain.
As it is shown, remarkable contribution to the effects of weakening
under the influence of magnetic field can be made by Joule heating by
eddy currents at magnetic field alterations.
Therefore, four different approaches to explanation of electro-
plastic effect have been reviewed. Each one is based on different mech-
anisms of electric current influence on strain. 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 disloca-
tion cores, that are involved in Molotskii’s model [32—34]. Other
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1053
mechanisms are also not discarded. For example, none of the above-
mentioned theories contradicts to enhanced phonon generation of
short-wave phonons by nonequilibrium electrons that, in turn, effec-
tively depinning dislocations from stoppers. Therefrom follows the ne-
cessity of performing more experimental investigations in order to
prove/disprove each of the theories separately. At planning of experi-
ments, the following important questions are to be solved.
For checking Bilyk’s et al. model [35, 36], it is necessary to separate
fast heating from electromagnetic influence.
For checking Molotskii’s et al. model [32—34], it is necessary to car-
ry out tests on the materials without paramagnetic dopants.
7. For estimation of the contribution from the induction part of elec-
tric field, which is caused by monopolar magnetic field change, an ex-
perimental study of the influence of pulse current density of flow
stress decrease during current pulses has been carried out. Compara-
tive experiments were conducted on the similar samples of high purity
(99.996%) polycrystalline nickel. Parameters of electric current den-
sity corresponded to the induction electric field strength generated by
monopolar pulses of magnetic field at creep tests (see Sect. 2). As it is
seen from Fig. 6 (right plot), during the current pulse, 1% decrease
of flow stress takes place that corresponds to 0.1% strain. These data
correspond to experimental results presented on Figs. 1—4.
ACKNOWLEDGEMENTS
This work is financially supported in part by the National Academy of
Sciences of Ukraine (under the contract 61-02-14) within the frame
collaboration between the National Academy of Sciences of Ukraine
and Russian Foundation for Basic Research (under the contract 14-02-
90248).
Fig. 6. Dependence of the polycrystalline nickel flow stress on the relative
strain: left plot–without of additional action of the electric current; right
plot–with periodic action of pulse electric current with density of 2.75·105
A/cm2.
1054 V. I. KARAS, E. V. KARASYOVA, A. V. MATS et al.
REFERENCES
1. S. Hayashi, S. Takahashi, and M. Yamamoto, J. Phys. Soc. Jpn., 25, No. 2: 910
(1968); J. Phys. Soc. Jpn., 30: 381 (1971).
2. I. A. Gindin, I. S. Lavrinenko, and I. M. Neklyudov, JETP Lett., 16, No. 6:
341(1972); Fizika Tverdogo Tela, 15, No. 4: 636 (1973) (in Russian).
3. O. A. Troitskii and V. I. Likhtman, Dokl. Akad. Nauk SSSR, 148, No. 2: 332
(1963) (in Russian).
4. V. Е. Gromov, V. Ya. Tsellermayer, and V. I. Bazaykin,
Elektrostimulirovannoye Volocheniye: Analiz Protsessa i Mikrostruktura
(Moscow: Nedra: 1996) (in Russian).
5. V. I. Spitsyn and О. А. Troitskii, Elektroplasticheskaya Deformatsiya Metallov
(Moscow: Nauka: 1985) (in Russian).
6. V. V. Stolyarov, Vestnik Nauchno-Tekhnicheskogo Razvitiya, No. 67: 35 (2013)
(in Russian).
7. R. B. Morgunov, Physics—Uspekhi, 47, No. 2: 131 (2004).
8. I. M. Nekludov, V. M. Azhazha, K. А. Yushchenko, V. I. Sokolenko, А. V. Mats,
V. М. Netesov, and V. V. Vartanov, Fizika i Khimiya Obrabotki Materialov,
No. 1: 84 (2011) (in Russian).
9. V. P. Lebedev and S. V. Savych, Vestnik KhNU. Seriya ‘Fizika’, No. 962,
Iss. 15: 88 (2011) (in Russian).
10. I. A. Gindin, S. F. Kravchenko, and Ya. D. Starodubov, Pribory i Tekhnika
Eksperimenta, No. 3: 269 (1963) (in Russian).
11. V. K. Aksenov, I. A. Gindin, V. P. Lebedev, and Ya. D. Starodubov, Fizika
Nizkikh Temperatur, 6, No. 1: 118 (1980) (in Russian).
12. V. K. Aksenov, I. A. Gindin, E. I. Druinskii, E. V. Karaseva, and
Ya. D. Starodubov, Fizika Nizkikh Temperatur, 3, No. 7: 922 (1977)
(in Russian).
13. I. M. Nekludov, Ya. D. Starodubov, and V. I. Sokolenko, Ukrayinskyy
Fizychnyy Zhurnal, 50, No. 8A: A113 (2005) (in Russian).
14. C. R. Chow and E. Nembach, Acta Met., 24, No. 5: 453 (1976).
15. V. K. Aksenov, I. A. Gindin, E. V. Karaseva, and Ya. D. Starodubov, Fizika
Nizkikh Temperatur, 4, No. 10: 1316 (1978) (in Russian).
16. D. N. Bolshutkin, V. A. Desnenko, and V. Ya. Illichev, Fizika Nizkikh
Temperatur, 2, No. 2: 256 (1976) (in Russian).
17. D. N. Bolshutkin, V. A. Desnenko, and V. Ya. Illichev, Fizika Nizkikh
Temperatur, 2, No. 12: 1544 (1976) (in Russian).
18. M. A. Vasiliev, Usp. Fiz. Met., 8, No. 1: 65 (2007) (in Russian).
19. M. I. Kaganov, V. Ya. Kravchenko, and V. D. Natsik, Physics—Uspekhi, 16,
No. 6: 878 (1974).
20. I. M. Neklyudov and N.V. Kamyshanchenko, Fizicheskie Osnovy Prochnosti i
Plastichnosti Metallov. Part 2: Defekty v Kristallakh (Moscow—Belgorod:
Izd-vo Belgorodskogo GU: 1997) (in Russian).
21. A. I. Landau and Yu. I. Gofman, Fizika Tverdogo Tela, 16, No. 11: 3427 (1974)
(in Russian).
22. A. Granato and K. Lücke, J. Appl. Phys., 27, No. 5: 583 (1956).
23. V. I. Dubinko, V. I. Karas, V. F. Klepikov, P. N. Ostapchuk, and
I. F. Potapenko, Voprosy Atomnoy Nauki i Tekhniki. Seriya ‘Fizika
Radiatsionnykh Povrezhdenij i Radiatsionnoye Materialovedenie’, 4—2 (94):
INFLUENCE OF ALTERNATING MAGNETIC FIELD ON CRYSTALS 1055
158 (2009) (in Russian).
24. V. Е. Zakharov and V. I. Karas’, Physics—Uspekhi, 56, No. 1: 49 (2013).
25. V. I. Karas’, A. M. Vlasenko,V. N. Voyevodin, V. I. Sokolenko, and
V. E. Zakharov, East Europe Physical Journal, 1, No. 1: 40 (2014).
26. N. Perrin and H. Budd, Phys. Rev. Lett., 28, No. 26: 1701 (1972).
27. V. I. Karas’, A. M. Vlasenko, V. I. Sokolenko, and V. E. Zakharov, JETP, 121,
No. 3: 499 (2015).
28. V. I. Karas’, A. M. Vlasenko, А. G. Zagorodniy, and V. I. Sokolenko, Proc. Int.
Conf. MSS-14 ‘Mode Conversion, Coherent Structure and Turbulence’
(Nov. 24—27, 2014) (Moscow: LENAND: 2014), p. 64.
29. V. E. Zakharov, V. I. Karas’, and А. М. Vlasenko, Proc. Int. Conf. MSS-14
‘Mode Conversion, Coherent Structure and Turbulence’ (Nov. 24—27, 2014)
(Moscow: LENAND: 2014), p. 34.
30. V. I. Karas’, V. I. Sokolenko, E. V. Karasyova, A. V. Mats, and A. M. Vlasenko,
Problems of Atomic Science and Technology. Series: Plasma Electronics and
New Acceleration Methods, No. 4 (98): 277 (2015).
31. A. F. Sprecher, S. L. Mannan, and H. Conrad, Acta Mater., 31, No. 7: 1145
(1986).
32. M. Molotskii and V. Fleurov, Phys. Rev. B, 52, No. 22: 829 (1995).
33. M. Molotskii and V. Fleurov, Phys. Rev. Lett., 78, No. 14: 2779 (1997).
34. M. I. Molotskii, Mater. Sci. Eng. A, 287: 248 (2000).
35. S. R. Bilyk, K. T. Ramesh, and T. W. Wright, J. Mechanics Phys. Solids, 53:
525 (2005).
36. J. Unger, M. Stiemer, L. Walden, F. Bach, H. Blum, and B. Svendsen, Proc. 2
nd
Int. Conf. on High Speed Forming (20—21 March, 2006, Dortmund) (Germany,
Dortmund: Institut für Umformtechnik und Leichtbau: 2006), p. 23.
<<
/ASCII85EncodePages false
/AllowTransparency false
/AutoPositionEPSFiles true
/AutoRotatePages /None
/Binding /Left
/CalGrayProfile (Dot Gain 20%)
/CalRGBProfile (sRGB IEC61966-2.1)
/CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2)
/sRGBProfile (sRGB IEC61966-2.1)
/CannotEmbedFontPolicy /Error
/CompatibilityLevel 1.4
/CompressObjects /Tags
/CompressPages true
/ConvertImagesToIndexed true
/PassThroughJPEGImages true
/CreateJobTicket false
/DefaultRenderingIntent /Default
/DetectBlends true
/DetectCurves 0.0000
/ColorConversionStrategy /CMYK
/DoThumbnails false
/EmbedAllFonts true
/EmbedOpenType false
/ParseICCProfilesInComments true
/EmbedJobOptions true
/DSCReportingLevel 0
/EmitDSCWarnings false
/EndPage -1
/ImageMemory 1048576
/LockDistillerParams false
/MaxSubsetPct 100
/Optimize true
/OPM 1
/ParseDSCComments true
/ParseDSCCommentsForDocInfo true
/PreserveCopyPage true
/PreserveDICMYKValues true
/PreserveEPSInfo true
/PreserveFlatness true
/PreserveHalftoneInfo false
/PreserveOPIComments true
/PreserveOverprintSettings true
/StartPage 1
/SubsetFonts true
/TransferFunctionInfo /Apply
/UCRandBGInfo /Preserve
/UsePrologue false
/ColorSettingsFile ()
/AlwaysEmbed [ true
]
/NeverEmbed [ true
]
/AntiAliasColorImages false
/CropColorImages true
/ColorImageMinResolution 300
/ColorImageMinResolutionPolicy /OK
/DownsampleColorImages true
/ColorImageDownsampleType /Bicubic
/ColorImageResolution 300
/ColorImageDepth -1
/ColorImageMinDownsampleDepth 1
/ColorImageDownsampleThreshold 1.50000
/EncodeColorImages true
/ColorImageFilter /DCTEncode
/AutoFilterColorImages true
/ColorImageAutoFilterStrategy /JPEG
/ColorACSImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/ColorImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/JPEG2000ColorACSImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/JPEG2000ColorImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/AntiAliasGrayImages false
/CropGrayImages true
/GrayImageMinResolution 300
/GrayImageMinResolutionPolicy /OK
/DownsampleGrayImages true
/GrayImageDownsampleType /Bicubic
/GrayImageResolution 300
/GrayImageDepth -1
/GrayImageMinDownsampleDepth 2
/GrayImageDownsampleThreshold 1.50000
/EncodeGrayImages true
/GrayImageFilter /DCTEncode
/AutoFilterGrayImages true
/GrayImageAutoFilterStrategy /JPEG
/GrayACSImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/GrayImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/JPEG2000GrayACSImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/JPEG2000GrayImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/AntiAliasMonoImages false
/CropMonoImages true
/MonoImageMinResolution 1200
/MonoImageMinResolutionPolicy /OK
/DownsampleMonoImages true
/MonoImageDownsampleType /Bicubic
/MonoImageResolution 1200
/MonoImageDepth -1
/MonoImageDownsampleThreshold 1.50000
/EncodeMonoImages true
/MonoImageFilter /CCITTFaxEncode
/MonoImageDict <<
/K -1
>>
/AllowPSXObjects false
/CheckCompliance [
/None
]
/PDFX1aCheck false
/PDFX3Check false
/PDFXCompliantPDFOnly false
/PDFXNoTrimBoxError true
/PDFXTrimBoxToMediaBoxOffset [
0.00000
0.00000
0.00000
0.00000
]
/PDFXSetBleedBoxToMediaBox true
/PDFXBleedBoxToTrimBoxOffset [
0.00000
0.00000
0.00000
0.00000
]
/PDFXOutputIntentProfile ()
/PDFXOutputConditionIdentifier ()
/PDFXOutputCondition ()
/PDFXRegistryName ()
/PDFXTrapped /False
/CreateJDFFile false
/Description <<
/ARA <FEFF06270633062A062E062F0645002006470630064700200627064406250639062F0627062F0627062A002006440625064606340627062100200648062B062706260642002000410064006F00620065002000500044004600200645062A064806270641064206290020064406440637062806270639062900200641064A00200627064406450637062706280639002006300627062A0020062F0631062C0627062A002006270644062C0648062F0629002006270644063906270644064A0629061B0020064A06450643064600200641062A062D00200648062B0627062606420020005000440046002006270644064506460634062306290020062806270633062A062E062F062706450020004100630072006F0062006100740020064800410064006F006200650020005200650061006400650072002006250635062F0627063100200035002E0030002006480627064406250635062F062706310627062A0020062706440623062D062F062B002E0635062F0627063100200035002E0030002006480627064406250635062F062706310627062A0020062706440623062D062F062B002E>
/BGR <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>
/CHS <FEFF4f7f75288fd94e9b8bbe5b9a521b5efa7684002000410064006f006200650020005000440046002065876863900275284e8e9ad88d2891cf76845370524d53705237300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c676562535f00521b5efa768400200050004400460020658768633002>
/CHT <FEFF4f7f752890194e9b8a2d7f6e5efa7acb7684002000410064006f006200650020005000440046002065874ef69069752865bc9ad854c18cea76845370524d5370523786557406300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c4f86958b555f5df25efa7acb76840020005000440046002065874ef63002>
/CZE <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>
/DAN <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>
/DEU <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>
/ESP <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>
/ETI <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>
/FRA <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>
/GRE <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>
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
/HRV (Za stvaranje Adobe PDF dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. Stvoreni PDF dokumenti mogu se otvoriti Acrobat i Adobe Reader 5.0 i kasnijim verzijama.)
/HUN <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>
/ITA <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>
/JPN <FEFF9ad854c18cea306a30d730ea30d730ec30b951fa529b7528002000410064006f0062006500200050004400460020658766f8306e4f5c6210306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103055308c305f0020005000440046002030d530a130a430eb306f3001004100630072006f0062006100740020304a30883073002000410064006f00620065002000520065006100640065007200200035002e003000204ee5964d3067958b304f30533068304c3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002>
/KOR <FEFFc7740020c124c815c7440020c0acc6a9d558c5ec0020ace0d488c9c80020c2dcd5d80020c778c1c4c5d00020ac00c7a50020c801d569d55c002000410064006f0062006500200050004400460020bb38c11cb97c0020c791c131d569b2c8b2e4002e0020c774b807ac8c0020c791c131b41c00200050004400460020bb38c11cb2940020004100630072006f0062006100740020bc0f002000410064006f00620065002000520065006100640065007200200035002e00300020c774c0c1c5d0c11c0020c5f40020c2180020c788c2b5b2c8b2e4002e>
/LTH <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>
/LVI <FEFF0049007a006d0061006e0074006f006a00690065007400200161006f00730020006900650073007400610074012b006a0075006d00750073002c0020006c0061006900200076006500690064006f00740075002000410064006f00620065002000500044004600200064006f006b0075006d0065006e007400750073002c0020006b006100730020006900720020012b00700061016100690020007000690065006d01130072006f00740069002000610075006700730074006100730020006b00760061006c0069007401010074006500730020007000690072006d007300690065007300700069006501610061006e006100730020006400720075006b00610069002e00200049007a0076006500690064006f006a006900650074002000500044004600200064006f006b0075006d0065006e007400750073002c0020006b006f002000760061007200200061007400760113007200740020006100720020004100630072006f00620061007400200075006e002000410064006f00620065002000520065006100640065007200200035002e0030002c0020006b0101002000610072012b00200074006f0020006a00610075006e0101006b0101006d002000760065007200730069006a0101006d002e>
/NLD (Gebruik deze instellingen om Adobe PDF-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. De gemaakte PDF-documenten kunnen worden geopend met Acrobat en Adobe Reader 5.0 en hoger.)
/NOR <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>
/POL <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>
/PTB <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>
/RUM <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>
/RUS <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>
/SKY <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>
/SLV <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>
/SUO <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>
/SVE <FEFF0041006e007600e4006e00640020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006f006d002000640075002000760069006c006c00200073006b006100700061002000410064006f006200650020005000440046002d0064006f006b0075006d0065006e007400200073006f006d002000e400720020006c00e4006d0070006c0069006700610020006600f60072002000700072006500700072006500730073002d007500740073006b00720069006600740020006d006500640020006800f600670020006b00760061006c0069007400650074002e002000200053006b006100700061006400650020005000440046002d0064006f006b0075006d0065006e00740020006b0061006e002000f600700070006e00610073002000690020004100630072006f0062006100740020006f00630068002000410064006f00620065002000520065006100640065007200200035002e00300020006f00630068002000730065006e006100720065002e>
/TUR <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>
/UKR <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>
/ENU (Use these settings to create Adobe PDF documents best suited for high-quality prepress printing. Created PDF documents can be opened with Acrobat and Adobe Reader 5.0 and later.)
>>
/Namespace [
(Adobe)
(Common)
(1.0)
]
/OtherNamespaces [
<<
/AsReaderSpreads false
/CropImagesToFrames true
/ErrorControl /WarnAndContinue
/FlattenerIgnoreSpreadOverrides false
/IncludeGuidesGrids false
/IncludeNonPrinting false
/IncludeSlug false
/Namespace [
(Adobe)
(InDesign)
(4.0)
]
/OmitPlacedBitmaps false
/OmitPlacedEPS false
/OmitPlacedPDF false
/SimulateOverprint /Legacy
>>
<<
/AddBleedMarks false
/AddColorBars false
/AddCropMarks false
/AddPageInfo false
/AddRegMarks false
/ConvertColors /ConvertToCMYK
/DestinationProfileName ()
/DestinationProfileSelector /DocumentCMYK
/Downsample16BitImages true
/FlattenerPreset <<
/PresetSelector /MediumResolution
>>
/FormElements false
/GenerateStructure false
/IncludeBookmarks false
/IncludeHyperlinks false
/IncludeInteractive false
/IncludeLayers false
/IncludeProfiles false
/MultimediaHandling /UseObjectSettings
/Namespace [
(Adobe)
(CreativeSuite)
(2.0)
]
/PDFXOutputIntentProfileSelector /DocumentCMYK
/PreserveEditing true
/UntaggedCMYKHandling /LeaveUntagged
/UntaggedRGBHandling /UseDocumentProfile
/UseDocumentBleed false
>>
]
>> setdistillerparams
<<
/HWResolution [2400 2400]
/PageSize [612.000 792.000]
>> setpagedevice
|
| id | nasplib_isofts_kiev_ua-123456789-112604 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1024-1809 |
| language | English |
| last_indexed | 2025-11-24T06:11:23Z |
| publishDate | 2016 |
| publisher | Інститут металофізики ім. Г.В. Курдюмова НАН України |
| record_format | dspace |
| spelling | Karas, V.I. Karasyova, E.V. Mats, A.V. Sokolenko, V.I. Vlasenko, A.M. Zakharov, V.E. 2017-01-23T18:27:37Z 2017-01-23T18:27:37Z 2016 Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals / V. I. Karas, E. V. Karasyova, A. V. Mats, V. I. Sokolenko, A. M. Vlasenko, and V. E. Zakharov // Металлофизика и новейшие технологии. — 2016. — Т. 38, № 8. — С. 1027-1055. — Бібліогр.: 36 назв. — англ. 1024-1809 DOI: 10.15407/mfint.38.08.1027 PACS: 61.72.Ff, 61.72.Hh, 62.20.Hg, 63.20.kd, 63.20.kp, 75.80.+q, 83.60.Np https://nasplib.isofts.kiev.ua/handle/123456789/112604 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. Наведено результати досліджень характеристик плазучости та активаційних параметрів пластичної течії полікристалічного ніклю (99,996% чистоти) за постійної температури у 77 К. Досліджувався вплив нестаціонарного магнетного поля напруженістю у 500 Е (гармонічні (50 Гц) та однополярні імпульси тієї ж частоти) на параметри плазучости ніклю. Експериментальні дослідження з впливу нестаціонарного магнетного поля змінного та сталого знаку за постійної температури проводилися, щоб оцінити внесок у рухливість дислокацій від взаємодії дислокацій з рухливими межами домен, а також від теплових ефектів, пов’язаних з індукційним електричним полем. Пропонований модель електропластичного ефекту (ЕПЕ) передбачає наступний механізм знеміцнення під дією електричного 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. Короткохвильові фонони, завдяки великому ґрадієнту напруги, ефективно відкріплюють дислокації від стопорів. Результати експериментів якісно збігаються з даними числових розрахунків. Представлены результаты исследования характеристик ползучести и активационных параметров пластического течения поликристаллического никеля (99,996% чистоты) при температуре 77 К. Было изучено влияние нестационарного магнитного поля напряжённостью 500 Э (гармонические (50 Гц) и монополярные импульсы той же частоты) на параметры ползучести никеля. Экспериментальные исследования влияния нестационарного магнитного поля постоянного и переменного знака при постоянной температуре проводились с целью оценить вклад в подвижность дислокаций от взаимодействия дислокаций с подвижными доменными границами, а также от тепловых эффектов, связанных с индукционным электрическим полем. Предлагаемая модель электропластического эффекта (ЭПЭ) подразумевает следующий механизм разупрочнения под действием электрического поля. Электрическое поле передаёт энергию подсистеме электронов проводимости, делая её термодинамически неравновесной. Неравновесные электроны, взаимодействуя с акустическими фононами, передают энергию преимущественно коротковолновой части фононного спектра. Коротковолновые фононы благодаря большому пространственному градиенту напряжения эффективно открепляют дислокации от стопоров. Экспериментальные результаты качественно совпадают с данными численных расчётов. This work is financially supported in part by the National Academy of Sciences of Ukraine (under the contract 61-02-14) within the frame collaboration between the National Academy of Sciences of Ukraine and Russian Foundation for Basic Research (under the contract 14-02-90248). en Інститут металофізики ім. Г.В. Курдюмова НАН України Металлофизика и новейшие технологии Физика прочности и пластичности Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals Вплив змінного магнетного поля на фізичні та механічні властивості кристалів Влияние переменного магнитного поля на физические и механические свойства кристаллов Article published earlier |
| spellingShingle | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals Karas, V.I. Karasyova, E.V. Mats, A.V. Sokolenko, V.I. Vlasenko, A.M. Zakharov, V.E. Физика прочности и пластичности |
| title | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals |
| title_alt | Вплив змінного магнетного поля на фізичні та механічні властивості кристалів Влияние переменного магнитного поля на физические и механические свойства кристаллов |
| title_full | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals |
| title_fullStr | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals |
| title_full_unstemmed | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals |
| title_short | Influence of Alternating Magnetic Field on Physical and Mechanical Properties of Crystals |
| title_sort | influence of alternating magnetic field on physical and mechanical properties of crystals |
| topic | Физика прочности и пластичности |
| topic_facet | Физика прочности и пластичности |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/112604 |
| work_keys_str_mv | AT karasvi influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT karasyovaev influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT matsav influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT sokolenkovi influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT vlasenkoam influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT zakharovve influenceofalternatingmagneticfieldonphysicalandmechanicalpropertiesofcrystals AT karasvi vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT karasyovaev vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT matsav vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT sokolenkovi vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT vlasenkoam vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT zakharovve vplivzmínnogomagnetnogopolânafízičnítamehaníčnívlastivostíkristalív AT karasvi vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov AT karasyovaev vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov AT matsav vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov AT sokolenkovi vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov AT vlasenkoam vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov AT zakharovve vliânieperemennogomagnitnogopolânafizičeskieimehaničeskiesvoistvakristallov |