Ab initio perspective of the 〈110〉 symmetrical tilt grain boundaries in bcc Fe: application of local energy and local stress

Bhattacharya, Somesh Kr.; Tanaka, Shingo; Shiihara, Yoshinori; Kohyama, Masanori

doi:10.1007/s10853-014-8038-1

Cited by 48 publications

(55 citation statements)

References 32 publications

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“…We provide here the grain boundary energies reported for two grain boundaries. The reporting references include [9][10][11][12][13][14][15], and the reported grain boundary energies range from 1.49 Jm While the approximative scheme can be tested for the Σ5(310)[001] grain boundary in the especially interesting regime of co-segregated grain boundaries, we are currently not aware of grain boundary energies for co-segregated sites for any other grain boundary. Consequently, we continue with a focus on the Σ5(310)[001] grain boundary.…”

Section: Ferritic Grain Boundary Hydrogen Embrittlement: Estimates Frmentioning

confidence: 99%

Linking Ab Initio Data on Hydrogen and Carbon in Steel to Statistical and Continuum Descriptions

Weikamp

Hüter

Spatschek

2018

Metals

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Abstract:We present a selection of scale transfer approaches from the electronic to the continuum regime for topics relevant to hydrogen embrittlement. With a focus on grain boundary related hydrogen embrittlement, we discuss the scale transfer for the dependence of the carbon solution behavior in steel on elastic effects and the hydrogen solution in austenitic bulk regions depending on Al content. We introduce an approximative scheme to estimate grain boundary energies for varying carbon and hydrogen population. We employ this approach for a discussion of the suppressing influence of Al on the substitution of carbon with hydrogen at grain boundaries, which is an assumed mechanism for grain boundary hydrogen embrittlement. Finally, we discuss the dependence of hydride formation on the grain boundary stiffness.

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Section: Ferritic Grain Boundary Hydrogen Embrittlement: Estimates Frmentioning

confidence: 99%

Linking Ab Initio Data on Hydrogen and Carbon in Steel to Statistical and Continuum Descriptions

Weikamp

Hüter

Spatschek

2018

Metals

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“…Note that the atomic Young's modulus is obtained by the atomic-volume change ratio in the uniaxial stretching and compression normal to the interface for the GB supercell. 34 The GB energies of these four STGBs are 0.43, 1.61, 1.49, and 1.71 J/m 2 , respectively. The Σ3 (112) GB, as the most stable GB in bcc Fe, consists of stable structural units with negligible changes in the first-neighbor bond length, which is akin to stacking faults or twins, and shows very small local-energy increases and negligible atomic stresses as seen in Fig.…”

Section: Segregation At Grain Boundaries and Local Energy/ Stress Anamentioning

confidence: 91%

“…For the segregation at looser sites with higher local energies in the original GB configurations, the energy gain is dominated by the term T 1 . In fact, for the "one-site" of the Σ3 (111) GB and "1a-site" of the Σ11 (332) GB in Table 2, the larger magnitudes of T 1 due to higher local energies of the sites "1" or "1a" in the original GBs lead 34 In each figure, the top panel shows the atomic configuration of the GB supercell, where two symmetric interfaces of one CSL period are contained, and structural units constituting one period are indicated by red lines. Atoms in blue and gray are those with different heights along the <110> direction, and numbers at atomic sites such as "1" ("1a", "1b", or "1c"), "2", "3", etc.…”

Section: Local-energy and Local-stress Analyses Of Si Segregation At mentioning

confidence: 99%

“…5 are a summary of the results in our previous article. 33,34 In each GB, increases in the local-energy Δε i , local tensile (positive) and compressive (negative) stresses σ i , and decreases in the atomic Young's moduli Y i are concentrated at the interface regions, but the degree of concentration depends on each GB. Note that the atomic Young's modulus is obtained by the atomic-volume change ratio in the uniaxial stretching and compression normal to the interface for the GB supercell.…”

Section: Segregation At Grain Boundaries and Local Energy/ Stress Anamentioning

confidence: 99%

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Mechanical properties of Fe-rich Si alloy from Hamiltonian

et al. 2017

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The physical origins of the mechanical properties of Fe-rich Si alloys are investigated by combining electronic structure calculations with statistical mechanics means such as the cluster variation method, molecular dynamics simulation, etc, applied to homogeneous and heterogeneous systems. Firstly, we examined the elastic properties based on electronic structure calculations in a homogeneous system and attributed the physical origin of the loss of ductility with increasing Si content to the combined effects of magneto-volume and D0 3 ordering. As a typical example of a heterogeneity forming a microstructure, we focus on grain boundaries, and segregation behavior of Si atoms is studied through high-precision electronic structure calculations. Two kinds of segregation sites are identified: looser and tighter sites. Depending on the site, different segregation mechanisms are revealed. Finally, the dislocation behavior in the Fe-Si alloy is investigated mainly by molecular dynamics simulations combined with electronic structure calculations. The solid-solution hardening and softening are interpreted in terms of two kinds of energy barriers for kink nucleation and migration on a screw dislocation line. Furthermore, the clue to the peculiar work hardening behavior is discussed based on kinetic Monte Carlo simulations by focusing on the preferential selection of slip planes triggered by kink nucleation.npj Computational Materials (2017) 3:10 ; doi:10.1038/s41524-017-0012-4 INTRODUCTION Mechanical properties of alloys originate from the behavior of electrons and atoms on the microscopic scale; however, the strength of atomic bonding does not directly relate to macroscopic mechanical properties such as the yield strength, fracture toughness, and fatigue resistance. This is because the microstructure on the mesoscale, which is composed of various defects such as impurities, grain boundaries, and dislocations, mediates or enhances the response of alloys against external forces, leading to fairly nonlinear and multiscale phenomena. Facing such a nonlinear nature associated with the strength and plastic deformation of alloys, identifying the controlling factors for the mechanical properties is a significantly difficult task, and clarifying the underlying physics at different length and time scales still remains a major challenge in materials science.The authors of the present article took up the challenge of this complicated problem with their particular theoretical and computational tools unique to each characteristic scale range. These tools are electronic structure calculations, the cluster variation method (CVM) of statistical mechanics, and molecular dynamics (MD) simulations, which may cover the atomic to mesoscopic scale ranges. By virtue of high-performance computers, some of the results obtained by the present calculations achieve a higher precision and reveal a clearer picture than those obtained by ordinary experiments.Among the various mechanical properties, the main focus of the present study is the solid-solut...

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“…To compute atomic stresses we utilized the concept of stress densities. Electronic-structure-based stress densities have been widely used to analyze local properties, e.g., at grain boundaries [25,[30][31][32][33][34][35][36], at surfaces [37][38][39], in superlattices [40], to analyze chemical bonding in molecules [41][42][43], in metal clusters [44][45][46], in metal complexes [47], in lithiumionic conductors [48], and in Si-Fe [49], as well as to analyze electronic shell structures of atoms [50]. In the present study, the method by Filippetti and Fiorentini [51], later modified to fit the plane-wave basis projector augmented-wave (PAW) method [37], was employed to compute the stress density.…”

Section: Computational Detailsmentioning

confidence: 99%

Correlation analysis of strongly fluctuating atomic volumes, charges, and stresses in body-centered cubic refractory high-entropy alloys

Ishibashi

Ikeda

Körmann

et al. 2020

Phys. Rev. Materials

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Local lattice distortions in a series of body-centered cubic alloys, including refractory high-entropy alloys, are investigated by means of atomic volumes, atomic charges, and atomic stresses defined by the Bader charge analysis based on first-principles calculations. Analyzing the extensive data sets, we find large distributions of these atomic properties for each element in each alloy, indicating a large impact of the varying local chemical environments. We show that these local-environment effects can be well understood and captured already by the first and the second nearest neighbor shells. Based on this insight, we employ linear regression models up to the second nearest neighbor shell to accurately predict these atomic properties. Finally, we find that the elementwiseaveraged values of the atomic properties correlate linearly with the averaged valence-electron concentration of the considered alloys.

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Ab initio perspective of the 〈110〉 symmetrical tilt grain boundaries in bcc Fe: application of local energy and local stress

Cited by 48 publications

References 32 publications

Linking Ab Initio Data on Hydrogen and Carbon in Steel to Statistical and Continuum Descriptions

Linking Ab Initio Data on Hydrogen and Carbon in Steel to Statistical and Continuum Descriptions

Mechanical properties of Fe-rich Si alloy from Hamiltonian

Correlation analysis of strongly fluctuating atomic volumes, charges, and stresses in body-centered cubic refractory high-entropy alloys

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