Effect of stochastic processes on structure formation in nanocrystalline materials under severe plastic deformation

Хоменко, Алексей Витальевич; Трощенко, Дар`я Сергіївна; Метлов, Л. С.

doi:10.1103/physreve.100.022110

Cited by 14 publications

(12 citation statements)

References 46 publications

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“…The noise strongly influences the pattern of a premelted film on the surface of ice, since it is very thin (∼ 10 nm). However, similar spectral densities of the signal have been obtained for the refinement of grain structures during severe plastic deformation of volume specimens without spatial restrictions [30].…”

Section: Analysis Of Friction Force Time Seriessupporting

confidence: 57%

“…This implies that the correlation time equals zero as for absolutely random process ("white noise"), which has ACF in the form of the Dirac function. However, comparison of the insets in figures 4a and 4b with the approximation of 𝛿-function [20,30] shows that an autocorrelation takes place within a certain correlation time. Thus, in the studied system correlated (colored) noise is realized.…”

Section: Analysis Of Friction Force Time Seriesmentioning

confidence: 90%

“…In particular, let us test the evolutionary dependencies for the presence of harmonic components that can be formed due to the influence of additive noncorrelated noise. The spectrum determination procedure is reduced to the application of the Fourier transform [28,30] that is determined by…”

Section: Analysis Of Friction Force Time Seriesmentioning

confidence: 99%

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Time series analysis of friction force at self-affine mode of ice surface softening

Хоменко¹,

Logvinenko²

2021

Condens. Matter Phys.

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The self-affine mode of ice softening during friction is investigated within the rheological model for viscoelastic medium approximation. The different modes of ice rubbing, determined by formation of surface liquid-like layer, are studied. The analysis of time series of friction force is carried out, namely Fourier analysis, construction of autocorrelation and difference autocorrelation functions. The spectral power law is detected for modes of crystalline ice as well as of a mixture of stable ice and metastable softening. The self-similarity and aperiodic character of corresponding time series of friction force are proved.

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Section: Analysis Of Friction Force Time Seriessupporting

confidence: 57%

Section: Analysis Of Friction Force Time Seriesmentioning

confidence: 90%

See 1 more Smart Citation

Time series analysis of friction force at self-affine mode of ice surface softening

Хоменко¹,

Logvinenko²

2021

Condens. Matter Phys.

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“…At the same time, it should be taken into account that under HPT, the dependence of the magnitude of the torsion torque on the number of revolutions can be approximated via a hyperbolic tangent. A more accurate dependence can be described within the framework of nonequilibrium evolutionary thermodynamics, where a connection is established between the processes of generation and annihilation of structural defects, as well as with materials hardening [ 16 , 31 ]. In this paper we will not investigate the dependence of the observed parameters on the torsion torque.…”

Section: Evolution Of Order Parameter and Steady State During Hptmentioning

confidence: 99%

Distribution of Order Parameter in Solids under High Pressure Torsion

et al. 2022

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Severe plastic deformation (SPD) can lead to various phase transformations. High-pressure torsion (HPT) is one of the most important variants of SPD. In principle, HPT can continue almost indefinitely long, as long as the plungers are not destroyed. However, the number of defects in a material during HPT deformation cannot increase indefinitely. When the rate of defects production becomes equal to the rate of their annihilation, a steady state or dynamic equilibrium is reached. Unexplored is the issue of establishing equilibrium at the initial stage of plunger torsion, when there is an angular acceleration. The parameters of the steady state are described here using the idea of an order parameter in solids in the framework of Landau phenomenological theory and the Landau‒Khalatnikov equation.

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“…Therefore, understanding unstable or metastable structures and their free energies is important for developing non-equilibrium thermodynamic model and predicting phase transition and microstructure evolution under SPP. A number of nonequilibrium thermodynamic models have been proposed for materials under SPP [74][75][76]. Panin et al [74] proposed that the energy associated with severe deformation can be described by the molar volume of defected structures.…”

Section: Defect Substructure Energeticsmentioning

confidence: 99%

Formation and dissociation of shear-induced high-energy dislocations: insight from molecular dynamics simulations

Chen¹,

Hu²,

Gwalani³

et al. 2022

Modelling Simul. Mater. Sci. Eng.

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Solid-phase processing (SPP) allows one to create complex microstructures, not achievable via thermal processing alone. The resulting structures exhibit a rich palette of defects, both thermal and non-thermal, including defect substructures, such as dislocation networks. It is essential to understand the mechanisms of deformation and defect structure formation to guide SPP towards achieving desired microstructures and material properties. In this study, large-scale molecular dynamics simulations are used to investigate the effects of inhomogeneous strain distribution, that mimics deformation conditions of tribological tests, on the evolution of defects under severe shear deformation in polycrystalline Al. Analysis of defect nucleation and reaction pathways reveals that strong geometric constraints suppress the nucleation and slide of low energy dislocation 1/2<110>{111} but promote the nucleation and slide of high energy dislocations, such as [1-10](001) and 1/2[1-1-2](1-11). A rough contact surface, characteristic to tribological tests, imposes an inhomogeneous stress field leading to inhomogeneous defect substructures due to location-dependent activation of slip systems. The results suggest that high-energy dislocations can dominate the evolution of grain structures in highly constrained environments, which should be considered in modeling plastic deformation and grain refinement during SPP.

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Effect of stochastic processes on structure formation in nanocrystalline materials under severe plastic deformation

Cited by 14 publications

References 46 publications

Time series analysis of friction force at self-affine mode of ice surface softening

Time series analysis of friction force at self-affine mode of ice surface softening

Distribution of Order Parameter in Solids under High Pressure Torsion

Formation and dissociation of shear-induced high-energy dislocations: insight from molecular dynamics simulations

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