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212 results on '"Korchuganov, A. V."'

5. Regularities of Structural Rearrangements in Single- and Bicrystals Near the Contact Zone

Author

Zolnikov, Konstantin P., Kryzhevich, Dmitrij S., Korchuganov, Aleksandr V., Choi, Seung-Bok, Series Editor, Duan, Haibin, Series Editor, Fu, Yili, Series Editor, Guardiola, Carlos, Series Editor, Sun, Jian-Qiao, Series Editor, Kwon, Young W., Series Editor, Ostermeyer, Georg-Peter, editor, Popov, Valentin L., editor, Shilko, Evgeny V., editor, and Vasiljeva, Olga S., editor

Published
2021
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8. Development of Defect Structure in Shock Loaded Two-Phase Gradient Nanograined Fe95Ni05.

Author

Korchuganov, A. V., Kryzhevich, D. S., Grigoriev, A. S., Berezikov, O. A., and Zolnikov, K. P.

Subjects
*BODY centered cubic structure, *FACE centered cubic structure, *DISLOCATION structure, *MOLECULAR structure, *THEORY of wave motion
Abstract

Molecular dynamics study of the influence of phase distribution on the response of two-phase nanocrystalline Fe95Ni05 samples with a gradient grained structure under shock loading was carried out. It was shown that the propagation of a shock wave causes direct and reverse FCC-BCC-FCC phase transformations in grains with the FCC structure, BCC-FCC/HCP phase transformations in lamellas with the BCC structure, as well as the nucleation of the HCP phase. The shock wave and the wave reflected from the rear surface initiated transformation of a significant part of the sample into the HCP phase. Shock wave propagation in the sample caused the appearance of two maxima on the curve of the time dependence of the HCP phase volume fraction. Time changes in the HCP phase fraction correlated with changes in the fraction of atoms belonging to intrinsic stacking faults and the dislocation density in the FCC phase. A large volume fraction of the intrinsic stacking faults, a higher dislocation density, and a lower volume fraction of the HCP phase were observed in the case of the sample with BCC lamellas only in one layer of grains compared to the sample with BCC lamellas in all grains under shock loading. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Development of Defect Structure in Shock Loaded Two-Phase Gradient Nanograined Fe95Ni05.

Author

Korchuganov, A. V., Kryzhevich, D. S., Grigoriev, A. S., Berezikov, O. A., and Zolnikov, K. P.

Subjects
BODY centered cubic structure, FACE centered cubic structure, DISLOCATION structure, MOLECULAR structure, THEORY of wave motion
Abstract

Molecular dynamics study of the influence of phase distribution on the response of two-phase nanocrystalline Fe95Ni05 samples with a gradient grained structure under shock loading was carried out. It was shown that the propagation of a shock wave causes direct and reverse FCC-BCC-FCC phase transformations in grains with the FCC structure, BCC-FCC/HCP phase transformations in lamellas with the BCC structure, as well as the nucleation of the HCP phase. The shock wave and the wave reflected from the rear surface initiated transformation of a significant part of the sample into the HCP phase. Shock wave propagation in the sample caused the appearance of two maxima on the curve of the time dependence of the HCP phase volume fraction. Time changes in the HCP phase fraction correlated with changes in the fraction of atoms belonging to intrinsic stacking faults and the dislocation density in the FCC phase. A large volume fraction of the intrinsic stacking faults, a higher dislocation density, and a lower volume fraction of the HCP phase were observed in the case of the sample with BCC lamellas only in one layer of grains compared to the sample with BCC lamellas in all grains under shock loading. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Plastic Deformation of Nanocrystalline Fe95Ni05 with Gradient Grained Structure under Shock Loading.

Author

Kryzhevich, D. S., Korchuganov, A. V., Grigoriev, A. S., Berezikov, O. A., and Zolnikov, K. P.

Subjects
*MATERIAL plasticity, *SHOCK waves, *THEORY of wave motion, *MOLECULAR dynamics, *STRUCTURAL dynamics
Abstract

A molecular dynamics simulation of structural transformations in nanocrystalline Fe95Ni05 samples with a single grain size and a gradient grained structure under shock loading is carried out. The shock loading condition is set by a constant-rate displacement of the non-deformable surface layer. It is found out that the generated shock wave is split into elastic and plastic components. An interaction of the plastic component with the grain boundaries leads to a generation of intrinsic stacking faults. The compressive stresses in the shock wave decrease as it propagates, which reduces the generation intensity of stacking faults and their density after stress relaxation. It is revealed that with a grain size increase, the density of the remaining stacking faults can significantly decrease, and the largest grains can completely restore the initial crystal structure after the shock wave propagation. By varying the grain structure, one can control the evolution of shock waves and the density of structural defects remaining in the material. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Computer simulation of surface modification of al crystallite under high energy treatment

Author

Kryzhevich, Dimitrij S., Korchuganov, Aleksandr V., and Zolnikov, Kostantin P.

Subjects
Finite element method, Ion implantation, Surfaces, Molecular dynamics, Structural defects, Grain Boundaries, Plasticity -- Mathematical models, Plasticitat, Elements finits, Mètode dels, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], Plasticitat -- Models matemàtics
Abstract

The simulation of structural changes in the surface region of Al crystallite during self-ion bombardment was carried out. The calculations were performed on the base of the molecular dynamics method. A many-body potential calculated in the approximation of the embedded atom method was used to describe the interatomic interactions. It is shown that atomic displacement cascades in the near-surface region were generated under ion irradiation. At relatively low energies the impact of the atomic displacement cascades not only lead to the generation of Frenkel pairs, but also to the nucleation of plastic deformation. That is due to the high-rate heating of the grains, causing their expansion and deformation in the stained conditions with the formation of stacking faults. Melting of surface layers takes place at high energies of irradiation. A crystallization process and a formation of a grain structure of the surface layers will be determined by the characteristics of the propagation of the crystallization front, which shape depends on the relative location, size and orientation of grains on the boundary of the liquid and solid phases.

Published
2017

46. Features of nucleation and evolution of defect structure in vanadium under constrained deformation

Author

Korchuganov, Aleksandr V., Zolnikov, Kostantin P., and Kryzhevich, Dimitrij S.

Subjects
Finite element method, Condensed Matter::Superconductivity, Plasticity -- Mathematical models, Plasticitat, Elements finits, Mètode dels, Plastic Deformation, Twins, Structure Fragmentation, Molecular Dynamics, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], Plasticitat -- Models matemàtics
Abstract

Atomic mechanisms of structural transformations leading to fragmentation in vanadium under deformation in constrained conditions without changing its volume are investigated on the basis of the molecular dynamics method. The process of formation of a fragmented structure in a deformed specimen can be divided into two stages. At the first stage, twins nucleate and grow in the crystallite. In the second stage, the orientation of lattice in twins may change due to the intersection of twins leading to their anisotropic deformation. In this case, the directions of stretching and compression of the crystal lattice in the deformed twin quite closely lie in the directions of stretching and compression of the whole crystallite.

Published
2017

47. Molecular dynamics simulation of nucleation and growth of defects in the alloy fe-cr in the conditions of high-energy loading

Author

Zolnikov, Kostantin P., Korchuganov, Aleksandr V., and Kryzhevich, Dimitrij S.

Subjects
Finite element method, Plasticity -- Mathematical models, Radiation Damage, Molecular Dynamics, Free Surface, Cascade of Atomic Displacements, Plasticitat, Elements finits, Mètode dels, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], Plasticitat -- Models matemàtics
Abstract

Features of primary radiation damages in the near-surface layers of the Fe-Cr crystallite were investigated. The calculations were based on the molecular dynamics method. It was found that the number of surviving defects at the generation of atomic displacement cascades near the free surfaces is almost twice their number than in case of cascade generation far away from the various interfaces. Besides it the cascades can knock out some atoms from the free surfaces and form some specific structural defects: craters, adatom islands, dislocation loops of vacancy type. The crystallographic orientation of the irradiated surfaces has a significant influence on the features of the material damage. Craters are much more frequently formed at the irradiation of the (111) surface. There is a correlation between the size of the vacancy loops and the number of adatoms on the free surface. The size of the vacancy loops formed by the irradiation of the (111) surface is slightly larger than the number of adatoms. The inverse relationship was found at the irradiation of the (110) surface of Fe-Cr crystallite.

Published
2017

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