First-Principles Calculation of Grain Boundary Excess Volume and Free Volume in Nanocrystalline and Ultrafine-Grained Aluminum

Uesugi, Tokuteru; Higashi, Kenji

doi:10.2320/matertrans.l-m2013816

Cited by 13 publications

(3 citation statements)

References 70 publications

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“…Apparently, GB configurations with smaller GB excess volumes have lower GB energies, especially for the GBs with E exc GB lower than 0.25 J m −2 . This correlation is consistent with that observed in ab initio or EAM studies of GBs in fcc metals [44][45][46]. This is because the GB energy reflects the degree of local structural disorder in the GB configuration, which should accord with the degree of deviation from the closed-packed configuration with the minimum volume.…”

Section: Local Analysissupporting

confidence: 88%

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

Xu¹,

Tanaka²,

Kohyama³

2021

Modelling Simul. Mater. Sci. Eng.

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Mg alloys are highly expected for the wide application in the next-generation industry, while significant improvement of the plasticity of polycrystalline Mg alloys is crucial. For this purpose, it is essential to get insights into the atomic configurations, energetics, and mechanical responses of Mg grain boundaries (GBs). In this study, we investigated the overall features of atomic configurations and energies of [ 1 1 ¯ 00 ] and [ 1 2 ¯ 10 ] symmetric tilt GBs in hcp Mg by density-functional theory. We systematically constructed atomic models of coincidence-site lattice GBs by the arrangement of structural units in the full range of rotation angles. We observed that special GBs show clear cusps in both the GB-energy and excess-volume curves against the rotation angle. The reason of the stability/instability of each GB configuration was analyzed by ab initio local energy and local stress based on Bader partitioning. The features of local energies and stresses in Mg GBs are quite different from those in other materials with covalent or partial-covalent bonding nature. We observed substantial variations of local energies, local stresses and Bader charges of GB atoms, and charge inhomogeneity in a GB region, reflecting the structural disorder. Stable GBs are characterized by modest ranges of such variations and by moderate charge homogeneity. These results could be utilized in general to understand the interface stability and deformation mechanism of Mg and other simple metals.

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Section: Local Analysissupporting

confidence: 88%

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

Xu¹,

Tanaka²,

Kohyama³

2021

Modelling Simul. Mater. Sci. Eng.

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“…In order to calculate the GB energy, E gb , according to [33][34][35][36][37][38][39], we used the following equation:…”

Section: Computational Detailsmentioning

confidence: 99%

Molecular dynamics simulations of $\langle \mathbf{1}\,\mathbf{0}\,\mathbf{\bar{1}}\,\mathbf{0}\rangle /\boldsymbol{\psi }$ tilt grain boundaries in ice

Prinzio¹,

Pereyra²

2016

Modelling Simul. Mater. Sci. Eng.

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In this paper, molecular dynamics simulations (MDS) of symmetric tilt ice grain boundaries are presented. The MDS were carried out using the GROMACS v4.5.5 program, and the water molecules were described using the TIP5P-Ew model. The grain boundary energies, , relative to those of the surface free energies, , were obtained as a function of the misorientation angle Ψ, and compared with the values experimentally obtained. The results show a good correspondence between the experimental and simulated values. The planar density of coincidence sites at the grain boundary planes, Γ, was obtained as a function of ψ. The Γ values were compared with the simulated values and a relation between the minimum of the simulated values and the maximum of the Γ values was observed, suggesting that the CSL theory is a good starting point to detect low energy ice GBs.

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“…Moreover, the interaction is expected to be activated because UFG metals fabricated by SPD processes have non-equilibrium GB, 17) which has excess GB energy. 18,19) In fact, the authors have proposed that grain-boundary sliding (GBS) was activated with decreasing strain rate ( ) in UFG interstitial-free (IF) steel, 20) but that mechanism remains unclear. Therefore, this study was conducted to ascertain the GBS mechanism and discuss the effect of dislocation − GB interaction on deformation by comparing deformation in CG and UFG metals.…”

Section: Introductionmentioning

confidence: 99%

Transition of Deformation Mechanism with Grain Refinement in Interstitial-Free Steel

et al. 2014

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To examine effects of the grain boundary (GB) and dislocation on the deformation mechanism for ultrafine-grained (UFG) and coarse-grained (CG) interstitial-free (IF) steels at room temperature, tensile tests and several types of microscopy were conducted for each steel. Atomic force microscopy revealed that the contribution of grain-boundary sliding (GBS) on deformation increased more prominently in UFG region than in CG region. Moreover, transmission electron microscopy revealed that dislocation motion was dominant in CG steel, where cell structure was formed with increasing strain. On the other hand, although dislocations moved in UFG steel, they did not tangle and piled up at GB, where interaction between GB and dislocation occurred markedly, causing significant GBS. Therefore, the dominant deformation mechanism changed from dislocation motion to GBS by decreasing grain size in IF steel.

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First-Principles Calculation of Grain Boundary Excess Volume and Free Volume in Nanocrystalline and Ultrafine-Grained Aluminum

Cited by 13 publications

References 70 publications

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

Molecular dynamics simulations of $\langle \mathbf{1}\,\mathbf{0}\,\mathbf{\bar{1}}\,\mathbf{0}\rangle /\boldsymbol{\psi }$ tilt grain boundaries in ice

Transition of Deformation Mechanism with Grain Refinement in Interstitial-Free Steel

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