Segregation of Carbon in α-Fe Symmetrical Tilt Grain Boundaries Studied by First-Principles Based Interatomic Potential

The effect of interstitial and substitutional impurities on grain boundary (GB) cohesion in the series of B2-TiMe alloys is studied from first principles using pseudopotential approach. It is shown that the TiMe Σ5(310) symmetrical tilt GB cohesion is reduced by the segregation of hydrogen while it is increased due to boron or carbon segregation. We analyze also the combined and accumulation effect of interstitial B (C) and H impurities on the change of the Griffith work.

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First-principles study of carbon segregation in bcc iron symmetrical tilt grain boundaries

Acta Materialia ◽

10.1016/j.actamat.2016.04.058 ◽

2016 ◽

Vol 115 ◽

pp. 259-268 ◽

Cited By ~ 38

Author(s):

Jingliang Wang ◽

Rebecca Janisch ◽

Georg K.H. Madsen ◽

Ralf Drautz

Keyword(s):

Grain Boundaries ◽

First Principles ◽

Carbon Segregation ◽

First Principles Study ◽

Bcc Iron ◽

Symmetrical Tilt

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Hydrogen Embrittlement at Cleavage Planes and Grain Boundaries in Bcc Iron—Revisiting the First-Principles Cohesive Zone Model

Materials ◽

10.3390/ma13245785 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5785

Author(s):

Abril Azócar Guzmán ◽

Jeongwook Jeon ◽

Alexander Hartmaier ◽

Rebecca Janisch

Keyword(s):

Hydrogen Embrittlement ◽

Single Crystal ◽

Grain Boundaries ◽

First Principles ◽

Cohesive Zone Model ◽

Tensile Tests ◽

Cohesive Strength ◽

Zone Model ◽

Bcc Iron ◽

Symmetrical Tilt

Hydrogen embrittlement, which severely affects structural materials such as steel, comprises several mechanisms at the atomic level. One of them is hydrogen enhanced decohesion (HEDE), the phenomenon of H accumulation between cleavage planes, where it reduces the interplanar cohesion. Grain boundaries are expected to play a significant role for HEDE, since they act as trapping sites for hydrogen. To elucidate this mechanism, we present the results of first-principles studies of the H effect on the cohesive strength of α-Fe single crystal (001) and (111) cleavage planes, as well as on the Σ5(310)[001] and Σ3(112)[11¯0] symmetrical tilt grain boundaries. The calculated results show that, within the studied range of concentrations, the single crystal cleavage planes are much more sensitive to a change in H concentration than the grain boundaries. Since there are two main types of procedures to perform ab initio tensile tests, different in whether or not to allow the relaxation of atomic positions, which can affect the quantitative and qualitative results, these methods are revisited to determine their effect on the predicted cohesive strength of segregated interfaces.

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Factors controlling segregation tendency of solute Ti, Ag and Ta into different symmetrical tilt grain boundaries of tungsten: First-principles and experimental study

Acta Materialia ◽

10.1016/j.actamat.2021.116868 ◽

2021 ◽

Vol 211 ◽

pp. 116868

Author(s):

Ahmed Tamer AlMotasem ◽

Teodor Huminiuc ◽

Tomas Polcar

Keyword(s):

Experimental Study ◽

Grain Boundaries ◽

First Principles ◽

Symmetrical Tilt

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An origin of excess vibrational entropies at grain boundaries in Al, Si and MgO: a first-principles analysis with lattice dynamics

Physical Chemistry Chemical Physics ◽

10.1039/d1cp00790d ◽

2021 ◽

Author(s):

T. Yokoi ◽

K. Ikawa ◽

A. Nakamura ◽

K. Matsunaga

Keyword(s):

Bond Length ◽

Grain Boundaries ◽

First Principles ◽

Lattice Dynamics ◽

Excess Entropy ◽

First Principle ◽

Length Changes

Excess vibrational entropies are examined by performing first-principle lattice dynamics for grain boundaries in MgO, Al and Si. Bond-length changes are critical for excess entropy, although their bonding nature is originally very different.

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First-Principles Study of Substitutional Impurity Segregation in Zirconia, Hafnia, and Yttria-Stabilized-Zirconia Grain Boundaries

2018 Joint Propulsion Conference ◽

10.2514/6.2018-4830 ◽

2018 ◽

Author(s):

Maziar Behtash ◽

Jian Luo ◽

Kesong Yang

Keyword(s):

Grain Boundaries ◽

First Principles ◽

Yttria Stabilized Zirconia ◽

Stabilized Zirconia ◽

Substitutional Impurity ◽

First Principles Study ◽

Impurity Segregation

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Structure and Stability of Grain Boundaries in Molybdenum with Segregated Carbon Impurities

MRS Proceedings ◽

10.1557/proc-578-405 ◽

1999 ◽

Vol 578 ◽

Cited By ~ 1

Author(s):

R. Janisch ◽

T. Ochs ◽

A. Merkle ◽

C. Elsässer

Keyword(s):

Ab Initio ◽

Grain Boundaries ◽

Density Functional ◽

Local Density ◽

Structural Parameters ◽

Carbide Phases ◽

Carbon Impurities ◽

Transmission Electron ◽

Local Density Functional Theory ◽

Symmetrical Tilt

AbstractThe segregation of interstitial impurities to symmetrical tilt grain boundaries (STGB) in bodycentered cubic transition metals is studied by means of ab-initio electronic-structure calculations based on the local density functional theory (LDFT). Segregation energies as well as changes in atomic and electronic structures at the ΣE5 (310) [001] STGB in Mo caused by segregated interstitial C atoms are investigated. The results are compared to LDFT data obtained previously for the pure Σ5 (310) [001] STGB in Mo. Energetic stabilities and structural parameters calculated ab initio for several crystalline Molybdenum Carbide phases with cubic, tetragonal or hexagonal symmetries and different compositions, MoCx, are reported and compared to recent high-resolution transmission electron microscopy (HRTEM) observations of MoCx, intergranular films and precipitates formed by C segregation to a Σ5 (310) [001] STGB in a Mo bicrystal.

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