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1.
G. E. Abrosimova A. S. Aronin S. V. Dobatkin I. I. Zver’kova D. V. Matveev O. G. Rybchenko E. V. Tat’yanin 《Physics of the Solid State》2007,49(6):1034-1039
The structural evolution of an amorphous Fe80B20 alloy subjected to severe plastic deformation at room temperature or at 200°C was studied. Deformation leads to the formation of α-Fe nanocrystals in an amorphous phase. After room-temperature deformation, nanocrystals are localized in shear bands. After deformation at 200°C, the nanocrystal distribution over the alloy is more uniform. Possible causes of the crystallization of the amorphous phase during severe plastic deformation are discussed. 相似文献
2.
N. I. Kourov V. G. Pushin A. V. Korolev V. V. Marchenkov E. B. Marchenkova V. A. Kazantsev H. W. Weber 《Physics of the Solid State》2011,53(1):91-99
The effect of one-percent substitution of iron for manganese on the physical (magnetic, electrical, thermal, and galvanomagnetic)
properties and the crystal structure of the Ni54Mn21Ga25 alloy has been investigated. It has been demonstrated that the deviation of the alloy composition from the stoichiometric
composition Ni50Mn25Ga25 leads to the formation of a mixed ferromagnetic-antiferromagnetic state. The atomic disordering and nanostructuring of the
alloys under investigation due to the severe plastic deformation by torsion in Bridgman anvils to sizes of 10–20 nm result
in the suppression of reversible magnetically controlled shape memory effects. 相似文献
3.
R. N. Eshchenko A. M. Patselov V. P. Pilyugin 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(9):1262-1265
The structural transformations in Ti3Al intermetallic compound at deuteration with concentrations x = 1.2 and 1.7, heating at 100–400°C, and shear deformation under pressure have been studied. It is established that at a
given deuterium concentration deuterides with fcc and orthorhombic lattices are formed; under severe shear deformation, nanocrystalline
and amorphous (or close to amorphous) deuterides arise. The reasons for the structure amorphization at deuteration and subsequent
plastic deformation are discussed. 相似文献
4.
S. Z. Shmurak A. P. Kiselev V. V. Sinitsyn I. M. Shmit’ko A. S. Aronin B. S. Red’kin E. G. Ponyatovskiĭ 《Physics of the Solid State》2006,48(1):51-57
Comparative spectroscopic studies of crystalline and amorphous samples of Eu2(MoO4)3 were carried out. Amorphous samples were obtained through exposure of the β' crystal phase to a high pressure of ∼9 GPa.
It was established that the transition to the amorphous state is accompanied by substantial changes both in the luminescence
spectrum and the luminescence excitation spectrum. The long-wavelength absorption edge is estimated to shift by ∼0.8 eV, which
is much more significant than in the case of amorphization of classical semiconductors. 相似文献
5.
6.
A. M. Glezer M. P. Plotnikova A. V. Shalimova S. V. Dobatkin 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(9):1233-1239
The basic regularities of variation in the structure and mechanical properties of amorphous Ni44Fe29Co15Si2B10 alloy at severe plastic deformation (SPD) in a Bridgman cell at different temperatures are considered. It is shown that SPD
is accompanied by homogeneous nanocrystallization, which is caused by the plastic flow mode. The transition from inhomogeneous
mode of plastic flow to a qualitatively different one has been detected. The SPD structural model of deformational “dissolving”
of crystals is proposed to explain why nanocrystals no more than 10 nm in size are observed during SPD. It is found that thermally
activated nanocrystallization may occur at very low temperatures (77 K) under very high stress and with a high concentration
of excess free volume. 相似文献
7.
N. I. Kourov V. G. Pushin A. V. Korolev V. A. Kazantsev E. B. Belozerov E. B. Marchenkova 《Technical Physics》2012,57(2):207-213
The effect of atomic disordering induced by melt quenching or severe plastic deformation via high-pressure torsion on the
physical properties (thermal expansion coefficient, electrical resistivity, thermoelectric power, magnetization) of a stoichiometric
Ni50Mn25Ga25 alloy and nonstoichiometric Ni50Mn28.5Ga21.5 alloys with 2 at % Cu or Co is studied in the temperature range 2 K ≤ T ≤ 900 K and the magnetic field range H ≤ 7 MA/m. 相似文献
8.
The specific heat C
total of crystalline and amorphous Eu2(MoO4)3 is measured in the temperature interval 4.5–30 K. The amorphous state is obtained by applying pressure ∼7 GPa at room temperature.
It is found that the specific heat of the crystal at T⩽7.5 K is described by a cubic function of temperature, while the specific
heat of the amorphous sample has a strongly non-Debye character in the entire experimental temperature interval. The curve
of C
total for amorphous europium molybdate is analyzed in a model of soft atomic potentials, and it is shown that it agrees well with
universal low-temperature anomalies of the specific heat of classical glasses obtained by quenching from the liquid.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 8, 623–627 (25 October 1998) 相似文献
9.
A. G. Gavriliuk V. V. Struzhkin I. S. Lyubutin M. I. Eremets I. A. Trojan V. V. Artemov 《JETP Letters》2006,83(1):37-41
The change of crystal structure in yttrium iron garnet Y3Fe5O12 was studied at room temperature at high pressures up to ∼55 GPa by the x-ray diffraction technique in diamond anvil cells.
At a pressure of about ∼50 GPa, a drastic change in the x-ray diffraction pattern was observed indicating the transition into
an amorphouslike state. When the pressure was increased, the bulk modulus of YIG was found to be 193 ± 4 GPa. It was also
found that the amorphous state was retained after decompression down to ambient pressure. From the shape of x-ray patterns
in the “amorphous” phase, it was concluded that the local atomic structure consists of iron-oxygen FeO6 octahedral complexes with disordered orientations of local axis and of randomly arranged others ion fragments with the overall
Y3Fe5O12 composition. For the amorphous phase, it was evaluated that the bulk modulus of FeO6 octahedral complexes is about 260 GPa.
The text was submitted by the authors in English. 相似文献
10.
G. Abrosimova A. Aronin O. Barkalov D. Matveev O. Rybchenko V. Maslov V. Tkach 《Physics of the Solid State》2011,53(2):229-233
The effect of multiple rolling at room temperature on the structure and crystallization of the Al85Ni6.1Co2Gd6Si0.9 amorphous alloy has been studied using transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction.
The total plastic strain is 33%. It has been shown that the deformation results in the formation of aluminum nanocrystals
with the average size that does not exceed 10–15 nm. The nanocrystals are formed in regions of localization of plastic deformation.
The deformation decreases the thermal effect of nanocrystallization (∼15%) as compared to the heat release at the first stage
of crystallization of the unstrained sample. The morphology, structure, and distribution of precipitates have been investigated.
Possible mechanisms of the formation of nanocrystals during the deformation have been discussed. 相似文献
11.
N. I. Kourov V. G. Pushin A. V. Korolev V. A. Kazantsev Yu. V. Knyazev N. N. Kuranova 《Physics of the Solid State》2011,53(7):1397-1403
The effect of severe plastic deformation by torsion (SPDT) in Bridgman anvils at a high pressure (6 GPa) on the physical properties
and crystal structure of the shape memory alloy Ti49.5Ni50.5 has been studied. The behavior of the thermal expansion, electrical resistivity, absolute differential thermopower, Hall
coefficient, magnetic properties, and optical characteristics of the amorphous/nanocrystalline and submicrocrystalline alloys
obtained by the SPDT with subsequent heat treatment at 800 K has been discussed. 相似文献
12.
A theoretical model has been proposed for describing the plastic flow and fracture of amorphous intercrystalline layers in
ceramic nanocomposites. The mechanism of plastic deformation has been considered as homogeneous nucleation and growth of liquidlike
phase inclusions subjected to plastic shear. It has been demonstrated using a nanoceramic material consisting of TiN nanocrystallites
and Si3N4 amorphous layers as an example that, when the length of the amorphous layer is reached and a considerable dislocation charge
is accumulated, these inclusions induce the formation and growth of Mode I–II cracks in neighboring amorphous layers. In this
case, the possibility of opening and growing the crack depends very strongly on the test temperature, the layer orientation,
and the size of nanoceramic grains. An increase in the temperature and the angle of orientation and a decrease in the size
of nanoceramic grains favor an increase in the crack resistance. 相似文献
13.
Methods of x-ray diffractometry are used to investigate the influence of plastic deformation on the state of the long-range
order in alloys with the L12, L12(M), and L12(MM) superstructure. It is demonstrated that the heterogeneous order-disorder phase transition accompanied by intensive accumulation
of antiphase boundaries occurs under plastic deformation. The antiphase boundaries play an important role in the destruction
of long-range order. Based on the available experimental results, a model of destruction of long-range order is constructed
that takes into account the dislocation mechanisms of accumulation of antiphase boundaries under deformation.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 9–24, January, 2006. 相似文献
14.
The effect of cold plastic deformation by upsetting (e = 1.13) on structure and hybridised bonds of carbon in the fcc Invar Fe-30.9%Ni-1.23% C alloy was studied by means of X-ray phase analysis and X-ray photoelectron spectroscopy. Carbon precipitates along grain boundaries and inside of grains in the alloy after annealing and plastic deformation were revealed. The presence of mainly sp2- and sp3-hybridised C–C bonds attributing to graphite and amorphous carbon as well as the carbon bonds with impurity atoms and metallic Fe and Ni atoms in austenitic phase were revealed in the annealed and deformed alloy. It was shown for the first time that plastic deformation of the alloy results in partial destruction of the graphite crystal structure, increasing the relative part of amorphous carbon, and redistribution of carbon between structural elements as well as in a solid solution of austenitic phase. 相似文献
15.
The anomalous phenomenon of the “double” yield point attributed with the “crystal ? amorphous state” phase transition during high-pressure torsion of Ti50Ni25Cu25 alloy has been analyzed experimentally and theoretically. Satisfactory correlation between experimental data and theoretical hypothesis has been found. 相似文献
16.
H. Morawiec T. Goryczka J. Lelatko K. Prusik A. Drdzeń 《The European physical journal. Special topics》2008,158(1):93-98
Deformation of polycrystalline Ni-Mn-Ga alloys was
studied for both the L21 parent phase and 10 M martensitic state. The
effect of deformation by compression up to the fracture on mechanical
behavior and structure change was studied for the inhomogeneous as-cast
state and after annealing at 900○C for 50 hours. The structure, after
deformation of the parent phase, observed by TEM reveals the presence of 10 M
and 14 M martensite in the matrix, whereas the deformation of 10 M martensite
does not show the change of the structure type. The stress-strain curves
were analyzed and compared with the earlier published results. 相似文献
17.
T. D. Varfolomeeva S. V. Popova A. G. Lyapin V. V. Brazhkin S. G. Lyapin Yu. P. Kudryavtsev S. E. Evsyukov 《JETP Letters》1997,66(4):255-260
Structural transformations of the cumulene form of amorphous carbyne which are induced by heating at high pressure (7.7 GPa)
are investigated. These can be described by the sequence amorphous phase — crystal — amorphous phase — disordered graphite.
Raman scattering shows that predominately the chain structure of carbyne remains at the first three stages. It was found that
the intermediate crystalline phase is an unknown modification of carbon whose structure is identified as cubic (a=3.145 Å). A mechanism of structural transformations in carbyne that involves the formation of new covalent bonds between
chains is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 237–242 (25 August 1997) 相似文献
18.
The microstructure of microcrystalline Fe78.1Cu1.2Nb3.2Si12.5 B10 alloy was examined by Mossbauer effect. The experimental results have shown that the microstructure of the alloy is composed
of about 70% the ordered phase Fe75+ySi25−y, 26% amorphous phase as grain boundaries and a little paramagnetic phase. y in Fe75+ySi25−y has preliminaryly determined to be in the range of 5–7. 相似文献
19.
A. M. Glezer M. P. Plotnikova A. V. Shalimova N. S. Perov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(9):1240-1244
The influence of severe plastic deformation in a Bridgman cell on the magnetic properties of amorphous alloys of metal-metalloid
type, Ni44Fe29Co15Si2B10, Fe74Si13B9Nb3Cu1, Fe57.5Ni25B17.5, Fe49.5Ni33B17.5, and Fe70Cr15B15, obtained by melt spinning, has been investigated. It is found that the saturation magnetization significantly changes (increases
or decreases), depending on the number of ferromagnetic and antiferromagnetic components in the alloy. It is suggested that
very high shear stress causes internal phase decomposition in the amorphous matrix into nanoscale regions, enriched or depleted
with ferromagnetic components. 相似文献
20.
In the work, we studied the evolution of structural and mechanical properties of 25Cr15Co hard magnetic alloy under shear deformation in Bridgman anvils at different rotation angles. It is shown that at the initial stage, severe plastic strains in a highly coercive (α1 + α2) state are localized in shear bands, in which the α1 and α2 phases are dissolved and an oversaturated a solid solution is formed. As this takes place, there arises a mixed structure consisting of misoriented fragments of the (α1 + α2) phase surrounded by interlayers of the a solid solution. A further increase in strain degree results in a single-phase nanocrystalline structure with a grain size of about 50 nm. It is found that the dissolution of the α1 phases in the α2 matrix under severe plastic deformation causes an increase in the strength characteristics and plasticity of 25Cr15Co alloy at all strain degrees under study. Maximum plasticity is found in the alloy with a mixed structure consisting of submicrocrystalline and cellular sites, and formation of nanocrystalline grains causes the plasticity to decrease somewhat. 相似文献