Nanosized structure formation in metals under the action of pulsed electric-explosion-induced plasma jets

Sarychev, V. D.; Vashchuk, E. S.; Будовских, Е. А.; Gromov, V. Е.

doi:10.1134/s1063785010070217

Cited by 9 publications

(7 citation statements)

References 2 publications

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“…The possibility of using the hydrodynamic approach to describe the intense plastic deformation is also implied by the phenomenon of deformation-induced amorphization investigated in [17,18]. The linear analysis of the Kelvin-Helmholtz instability developed in our works [1][2][3] to various technological problems is presented in [19]. A mechanism and a mathematical model for the formation of shear bands from the position of the Kelvin-Helmholtz instability are proposed in [20].…”

Section: Problem Formulationmentioning

confidence: 99%

“…Hydrodynamic concept to determine the mechanism for forming nanostructured elements under external actions was first used when studying effects of heterogeneous plasma flows, created by electric explosion of conductors, on metals [1]. This work introduces a hypothesis that nanostructures in a metal are formed because of the Kelvin-Helmholtz instability.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Nanoparticles Formation by Mechanism of Kelvin-Helmholtz Instability

Vladimir¹

2017

Int J Nanoparticles Nanotech

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The Kelvin-Helmholtz instability is analyzed at scales of micro-and nano-structures. We have studied the stability of a plane motionless layer of a two-layer incompressible viscous fluid using the Navier-Stokes equations for linear and nonlinear analyses. The effects of viscosity were assumed to occur at an interface with a flow inside the layers to be irrotational. A dispersion equation was developed for small perturbations, which is similar in form to the dispersion equation appeared in earlier papers, provided the short-wave approximation is applied. We first determined: 1) The dependence of the perturbation decrement for a viscous two-layer fluid that has two maxima, with the first maximum being within the wavelengths ranging from 100 to 300 nm and the second from 1 to 3 μm; 2) The approximate analytic dependence of wavenumber that contains the maximum for the perturbation decrement on input parameters for a problem (densities of both layers, their thicknesses, viscosity, surface tension, velocity of layer motion, a coefficient of resistance). It allows us to size up the emerging vortex structures under different conditions. The range of input parameters for the problem was determined, where two maxima relating to the dependence of disturbance decrement were observed. To verify the results after performing linear analysis, the Level Set Method was used for analyzing nonlinear equations. The results of calculations prove that linear analysis adequately describes how vortex structures in various sizes are formed.

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Section: Problem Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of Nanoparticles Formation by Mechanism of Kelvin-Helmholtz Instability

Vladimir¹

2017

Int J Nanoparticles Nanotech

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“…С точки зрения гидродинамики на таких поверхностях имеет место абсолютная неустойчивость поверхностей раздела, так называемая неустойчивость Кельвина-Гельмгольца (НКГ), развитие которой приводит к формированию ячеек кристаллизации с размером, пропорциональным длинам волн максимального роста. Возникновением и развитием НКГ объясняется образование наноструктур при воздействии на поверхность концентрированных потоков энергии [26,27] и в условиях интенсивной пластической деформации [28,29]. В работе [27] численно исследовано дисперсионное уравнение, полученное в приближении вязко-потенциаль ной модели [30].…”

Section: Introductionunclassified

Model of nanostructural layers formation at long-term operation of rails

Sarychev

Невский

Кормышев

et al. 2020

Izv. vysš. učebn. zaved., Čern. metall.

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A mathematical model was developed and a mechanism was proposed for the formation of nanoscale structural-phase states on the example of rail steel at long-term operation. It was believed that during intense plastic deformations, the material behaves like a viscous incompressible fluid. In order to take into account the sliding of the wheel relative to the rail, a two-layer fluid model was proposed, the top layer of which slides at a certain speed relative to the first. In this case, the Kelvin-Helmholtz instability develops. For each layer, we have written the Navier-Stokes equations and kinematic and dynamic boundary conditions. Solution of the obtained system in the form of normal perturbation modes was carried out on the basis of assumption of the viscous-potential material flow. In this approximation, it was believed that viscosity effects occur only at the layer interface. A dispersion equation was derived, which was analyzed using a graphical representation of the functions included in the analytical solution. A range of characteristics of the material and parameters of the external influence (the velocity of the layer) was established, at which two peaks are observed in dependence of disturbances growth rate on the wave number. The first (hydrodynamic) maximum is due to the motion of the layers relative to each other; the second is associated with the effects of fluid viscosity. Approximate formulas were obtained for dependence of the growth rate of perturbations on the wave number. Conditions for realization of only one maximum were found. The viscously determined maximum at slip velocities of the order of 1 m/s can be in the nanoscale wavelength range. Assuming that the white layer in the rails during long-term operation is formed mainly due to the action of intense plastic deformations, we believe that the obtained results detail the mechanism of white layers formation in the rails in this case.

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“…In [15] mechanism is proposed that explains the formation of a thin nanostructural near-surface layer in the alloyed zone formed during the metal surface fusion treatment under the action of a pulsed plasma jet generated by the electric explosion of conductors. The proposed mechanism is based upon the development of the Kelvin-Helmholtz (KH) instability at the plasma-melt interface.…”

Section: Introductionmentioning

confidence: 99%

“…The size of this drop corresponds to the wavelength with the greatest decrement. The dependence of the decrement of the wavelength in the nanoscale range was obtained numerically in [15]. …”

mentioning

confidence: 99%

Model of formation of droplets during electric arc surfacing of functional coatings

Sarychev

Granovskii

Невский

et al. 2016

AIP Conference Proceedings

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Predictions of metal droplet formation in gas metal arc welding. II. Journal of Applied Physics 84, 3530 (1998) Abstract. The mathematical model was developed for the initial stage of formation of an electrode metal droplet in the process of arc welding. Its essence lies in the fact that the presence of a temperature gradient in the boundary layer of the molten metal causes thermo-capillary instability, which leads to the formation of electrode metal droplets. А system of equations including Navier-Stokes equations, heat conduction and Maxwell's equations was solved as well as the boundary conditions for the system electrodes-plasma. Dispersion equation for thermo-capillary waves in the linear approximation for the plane layer was received and analyzed. The values of critical wavelengths, at which thermocapillary instability appears in the nanometer wavelength range, were found. The parameters at which the mode of a finedroplet transfer of the material takes place were theoretically defined.

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Nanosized structure formation in metals under the action of pulsed electric-explosion-induced plasma jets

Cited by 9 publications

References 2 publications

Simulation of Nanoparticles Formation by Mechanism of Kelvin-Helmholtz Instability

Simulation of Nanoparticles Formation by Mechanism of Kelvin-Helmholtz Instability

Model of nanostructural layers formation at long-term operation of rails

Model of formation of droplets during electric arc surfacing of functional coatings

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