Key role of excess atomic volume in structural rearrangements at the front of moving partial dislocations in copper nanocrystals

Psakhie, S. G.; Zolnikov, Konstantin; Крыжевич, Д. С.; Korchuganov, A. V.

doi:10.1038/s41598-019-40409-9

Cited by 35 publications

(5 citation statements)

References 35 publications

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“…It is clearly seen (black curve) that the atomic volume increases abruptly during the phase transformation. This behavior is in good agreement with the previous experimental and simulation data [31,32], which show that the generation of structural defects and phase transformations are always accompanied by the formation of an excess atomic volume. The volume of the Voronoi cell for atom A increases by ~2.7% during the bcc-fcc transformation.…”

Section: Atomic Mechanism Of the Bcc-fcc/hcp Structural Phase Transfo...supporting

confidence: 92%

Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading

Korchuganov

Крыжевич

Zolnikov

2022

Metals

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In this paper, we used molecular dynamics simulations to study the atomic mechanisms of phase transformations, plasticity features, and mechanical properties of two-phase Fe95Ni5 (at. %) samples with a gradient nanograined structure under uniaxial deformation and shear. The simulated samples with a uniform distribution of Ni atoms are composed of fcc grains from 10 to 30 nm in size, which in turn contain bcc interlayers in the form of lamellae of various distribution and size. It was shown that uniaxial loading or shear causes the bcc-fcc phase transformation in the lamellae. In the vast majority of cases, phase transformations are initiated at the junction of lamellae and grain boundaries. Deformation-induced phase transformations in lamellae occur at the front of bands propagating from grain boundaries. Grains larger than ~15 nm can have several bands or regions with differently orientated fcc lattices, whose meeting results in grain fragmentation. It was found that the atomic volume increases abruptly during the bcc-fcc structural phase transformation. The Kurdyumov–Sachs orientation relation is valid between the initial bcc and formed fcc structures. It was shown that the volume fraction and spatial distribution of the bcc phase significantly affect the yield stress of the sample. The yield stress can be increased by forming the bcc phase only in large-grained layers. This behavior is associated with the fragmentation of large grains, and consequently with grain refinement, which, in accordance with the Hall–Petch relation, improves the strength of the material.

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Section: Atomic Mechanism Of the Bcc-fcc/hcp Structural Phase Transfo...supporting

confidence: 92%

Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading

Korchuganov

Крыжевич

Zolnikov

2022

Metals

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“…The study of atomic mechanisms of plasticity nucleation in metallic materials is crucial for design of new materials for different practical applications. Experimental, theoretical and computer simulation studies show that the nucleation of plasticity is realized by structural transformations on the atomic scale [1][2][3][4][5]. The features of these transformations largely depend on the stress distribution which is determined by the internal structure of the material.…”

Section: Institute Of Strength Physics and Materials Science Sb Ras mentioning

confidence: 99%

Influence of Grain Structure on the Mechanisms of Plasticity Nucleation in BCC Metal Under Mechanical Loading

2020

Mezhdunarodnaya Konferentsiya "Fizicheskaya Mezomekhanika. Materialy S Mnogourovnevoy Ierarkhicheski Organizovannoy Strukturoy

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“…Despite the high information content of such studies, it is difficult to analyze the results due to the complex deformation pattern. For the clearer and simpler interpretation of the indentation results, it is convenient to use an extended indenter of a cylindrical shape [35][36][37]. For this choice of the indenter, the contact region is linearly extended from one face of the sample to the other.…”

Section: Peculiarities Of Plasticity Nucleation In Metals Under Nanoimentioning

confidence: 99%

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

Zolnikov

Крыжевич

Korchuganov

2020

Springer Tracts in Mechanical Engineering

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The chapter is devoted to the analysis of the features of local structural rearrangementsin nanostructured materialsunder shear loadingand nanoindentation. The study was carried out using molecular dynamics-based computer simulation. In particular, we investigated the features of symmetric tilt grain boundary migration in bcc and fcc metals under shear loading. The main emphasis was on identifying atomic mechanisms responsible for the migration of symmetric tilt grain boundaries. We revealed that grain boundaries of this type can move with abnormally high velocities up to several hundred meters per second. The grain boundary velocity depends on the shear rate and grain boundary structure. It is important to note that the migration of grain boundary does not lead to the formation of structural defects. We showed that grain boundary moves in a pronounced jump-like manner as a result of a certain sequence of self-consistent displacements of grain boundary atomic planes and adjacent planes. The number of atomic planes involved in the migration process depends on the structure of the grain boundary. In the case of bcc vanadium, five planes participate in the migration of the Σ5(210)[001] grain boundary, and three planes determine the Σ5(310)[001] grain boundary motion. The Σ5(310)[001] grain boundary in fcc nickel moves as a result of rearrangements of six atomic planes. The stacking order of atomic planes participating in the grain boundary migration can change. A jump-like manner of grain boundary motion may be divided into two stages. The first stage is a long time interval of stress increase during shear loading. The grain boundary is motionless during this period and accumulates elastic strain energy. This is followed by the stage of jump-like grain boundary motion, which results in rapid stress drop. The related study was focused on understanding the atomic rearrangements responsible for the nucleation of plasticity near different crystallographic surfaces of fcc and bcc metals under nanoindentation. We showed that a wedge-shaped region, which consists of atoms with a changed symmetry of the nearest environment, is formed under the indentation of the (001) surface of the copper crystallite. Stacking faults arise in the (111) atomic planes of the contact zone under the indentation of the (011) surface. Their escape on the side free surface leads to a step formation. Indentation of the (111) surface is accompanied by nucleation of partial dislocations in the contact zone subsequent formation of nanotwins. The results of the nanoindentation of bcc iron bicrystal show that the grain boundary prevents the propagation of structural defects nucleated in the contact zone into the neighboring grain.

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Key role of excess atomic volume in structural rearrangements at the front of moving partial dislocations in copper nanocrystals

Cited by 35 publications

References 35 publications

Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading

Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading

Influence of Grain Structure on the Mechanisms of Plasticity Nucleation in BCC Metal Under Mechanical Loading

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

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