Microscopics of fluctuations of the energy of atoms in solids

Slutsker, A. I.; Mihailin, A I; Slutsker, I A

doi:10.1070/pu1994v037n04abeh000017

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…Defects of this type affect the low-temperature properties of nanocrystalline/amorphous materials and can be considered as carriers of plastic deformation. The most well–known theory taking account of the presence of an inelastic zone in front of the crack is the Leonov–Panasyuk–Dugdale theory [ 39 ]. Under the conditions of low-temperature embrittlement of the composite, it can be assumed that a zone of forced plasticity occurs in front of the crack front, and this zone develops by overcoming the internal friction with the release of additional heat, which leads to local heating of the material in the vicinity of the crack tip.…”

Section: Resultsmentioning

confidence: 99%

“…Taking into account the above-discussed theoretical concepts based on the analysis of physical phenomena [ 16 , 36 , 37 , 38 , 39 , 40 ] describing the fracture process in a nanocrystalline/amorphous material, a physical model of the heating of the region in the vicinity of the crack tip was formulated. The heat transfer by the mechanism of thermal conductivity with internal heat sources in the investigated solid material is described by the differential equation of thermal conductivity (Fourier differential equation).…”

Section: Resultsmentioning

confidence: 99%

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Physical Mechanism of Nanocrystalline Composite Deformation Responsible for Fracture Plastic Nature at Cryogenic Temperatures

Qiao,

Ushakov,

Safronov

et al. 2024

Nanomaterials

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In this work, we consider the physical basis of deformation and fracture in layered composite nanocrystalline/amorphous material–low-melting crystalline alloy in a wide temperature range. Deformation and fracture at the crack tip on the boundary of such materials as nanocrystalline alloy of the trademark 5BDSR, amorphous alloy of the trademark 82K3XSR and low-melting crystalline alloy were experimentally investigated. The crack was initiated by uniaxial stretching in a temperature range of 77–293 K. A theoretical description of the processes of deformation and fracture at the crack tip is proposed, with the assumption that these processes lead to local heating and ensure the plastic character of crack growth at liquid nitrogen temperatures. The obtained results improve the theoretical understanding of the physics of fracture at the boundary of nanocrystalline and crystalline alloys in a wide temperature range. The possibility of preserving the plastic nature of fracture in a thin boundary layer of crystalline–nanocrystalline material at cryogenic temperatures has been experimentally shown.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Physical Mechanism of Nanocrystalline Composite Deformation Responsible for Fracture Plastic Nature at Cryogenic Temperatures

Qiao,

Ushakov,

Safronov

et al. 2024

Nanomaterials

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“…It has been proved that the atomic diffusion in BMGs is strongly dependent on the energy fluctuation [17]. If the intensity of atomic thermal vibration becomes weak, the energy fluctuation created by the collision between neighboring atoms will obviously decrease, then the diffusion of those atoms would be obstructed [18][19]. Among the present alloy system, Fe 28 Co 20 Cr 15 Mo 14 C 15 B 6 Y 2 alloy with the lowest thermal conductivity is expected to possess the worst atomic diffusion ability, and resisting the crystallization.…”

Section: Methodsmentioning

confidence: 99%

Effects of High Co Contents in Fe-Cr-Mo-C-B-Y Alloy on the Glass Forming and the Mechanical Properties

Chen

Liu

Zhou

et al. 2013

AMR

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A series of wedge shape Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) samples were prepared by copper mold suction casting method. The effects of high Co contents on glass forming ability (GFA) and mechanical properties of Fe24+XCo24-X Cr15Mo14C15B6Y2 bulk metallic glasses (BMG) were investigated, respectively. The glass forming ability of bulk amorphous Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) and Fe41Co7Cr15Mo14C15B6Y2 alloys have been researched. Simultaneously, the thermal conductivity parameters of those alloys were tested. The maximum thickness of amorphous region of wedge-shaped samples are dm =7.80 mm for Fe28Co20Cr15Mo14C15B6Y2, dm =7.10 mm for Fe41Co7Cr15Mo14C15B6Y2 and the thermal conductivity are λ=7.11 w.m-1.k-1 and 7.19 w.m-1.k-1, the thermal diffusivity are α=1.875 mm2/s and 1.905 mm2/s for Fe28Co20Cr15Mo14C15B6Y2 and Fe41Co7Cr15Mo14C15B6Y2 BMGs, respectively. The glass forming ability of Fe28Co20Cr15Mo14C15B6Y2 alloy is bigger than that of well known Fe41Co7Cr15Mo14C15B6Y2 alloy. With the change of Co content, the Vickers hardness of Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) change from 1292 to 1322Hv.

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“…В этих процессах особое состояние системы, именуемое слабоустойчивым, может быть связано с состоянием атомного ансамбля в поле механических напряжений и тепловых флуктуаций, совместное действие которых позволяет преодолеть потенциальный барьер процесса [6,7]. Моделирование таких флуктуаций в атомной системе позволило установить, что сильная флуктуация энергии атомов может представлять собой достаточно устойчивое, динамическое состояние [8]. Особенностью тепловых колебаний атомов являются «динамические коллективные (кооперативные) атомные смещения», представляющие собой упорядоченные смещения групп атомов [9].…”

Section: Introductionunclassified

Weakly Stable State of the Crystal Lattice of Metals and Alloys

Макаров¹,

Плотников²,

Dem’yanov³

et al. 2019

LOM

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The state of the crystalline medium under the conditions of thermal fluctuations and mechanical stresses called weakly stable is determined by the displacement of atoms at a relative distance of 0.15-0.20 from the equilibrium positions. Such a displacement of the atoms follows the Lindemann criteria of the crystals melting, and the state of atomic ensemble can be described as delocalized one. The state of delocalization means the transition of the atom through the maximum of interaction force and is characterized by a strong anharmonic component of oscillations and softening of elastic modules. It is the state of delocalization of the atomic ensemble that is the weakly stable state of the crystal lattice. Weakly stable state of metal materials is manifested in a wide range of phenomena. These include abnormal reduction of elastic modules in thermoelastic martensitic transformations, second-order structural-phase transitions with the formation of long-period structures, abrupt plastic deformation, most clearly manifested in aluminium and its alloys, increasing the rate of deformation during creep in the ultrasonic field under static load. This paper presents the results of the analysis of the weakly stable state of the crystalline medium, especially in plastic deformation, that is, in the processes caused by the displacement of atoms from the equilibrium position. In these processes, the weakly stable state of the system can occur in the field of mechanical stresses and thermal fluctuations when the acoustic field of standing waves is applied, formed by primary acoustic emission signals, the combined action of which allows to overcome the potential barrier. In this state, the oscillatory displacement of the acoustic standing wave acts as a factor of self-organization, that is, it may be sufficient to activate the correlated dislocation slip, in fact, the athermal above-barrier slip in the weakly stable state of the crystal lattice.

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Microscopics of fluctuations of the energy of atoms in solids

Cited by 6 publications

References 13 publications

Physical Mechanism of Nanocrystalline Composite Deformation Responsible for Fracture Plastic Nature at Cryogenic Temperatures

Physical Mechanism of Nanocrystalline Composite Deformation Responsible for Fracture Plastic Nature at Cryogenic Temperatures

Effects of High Co Contents in Fe-Cr-Mo-C-B-Y Alloy on the Glass Forming and the Mechanical Properties

Weakly Stable State of the Crystal Lattice of Metals and Alloys

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