Structures and transitions in bcc tungsten grain boundaries and their role in the absorption of point defects

Frolov, Timofey; Zhu, Qiang; Oppelstrup, Tomas; Marian, Jaime; Rudd, Robert E.

doi:10.1016/j.actamat.2018.07.051

Cited by 53 publications

(20 citation statements)

References 98 publications

(149 reference statements)

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“…While the energy difference at 0 K was only few percent and was found to be both positive and negative for different GBs, all these boundaries transformed from NK to SK at high temperature [22]. Similar multiplicity of structures and preferred high-temperature GB phases have been demonstrated for [110] symmetric tilt GBs in bcc tungsten [23,61]. The apparent high-temperature stability of certain types of GB structures in these systems is not well understood.…”

Section: Discussionmentioning

confidence: 86%

Free energy of grain boundary phases: Atomistic calculations for Σ5(310)[001] grain boundary in Cu

Freitas

Rudd

Asta

et al. 2018

Phys. Rev. Materials

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Atomistic simulations are employed to demonstrate the existence of a well-defined thermodynamic phase transformation between grain boundary (GB) phases with different atomic structures. The free energy of different interface structures for an embedded-atom-method model of the Σ5(310)[001] symmetric tilt boundary in elemental Cu is computed using the nonequilibrium Frenkel-Ladd thermodynamic integration method through molecular dynamics simulations. It is shown that the free-energy curves predict a temperature-induced first-order interfacial phase transition in the GB structure in agreement with computational studies of the same model system. Moreover, the role of vibrational entropy in the stabilization of the high-temperature GB phase is clarified. The calculated results are able to determine the GB phase stability at homologous temperatures less than 0.5, a temperature range particularly important given the limitation of the methods available hitherto in modeling GB phase transitions at low temperatures. The calculation of GB free energies complements currently available 0 K GB structure search methods, making feasible the characterization of GB phase diagrams. arXiv:1807.03274v2 [cond-mat.mtrl-sci]

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Section: Discussionmentioning

confidence: 86%

Free energy of grain boundary phases: Atomistic calculations for Σ5(310)[001] grain boundary in Cu

Freitas

Rudd

Asta

et al. 2018

Phys. Rev. Materials

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“…Under cumulative radiation, amounts of defects segregate to the GBs where defects have low formation energy. Researchers investigated the effect of the radiation defects at the GB on the GB structure [56][57][58][59]. In face-centered cubic metals of poly-crystallines Cu, Ag, Au and Ni, it is shown that the absorption of point Vs/SIAs can strongly modify the GB structure, inducing structural transformations of the GB.…”

Section: Effect Of Radiation-defects On the Gb Structurementioning

confidence: 99%

“…The presence of multiple metastable GB phases greatly enhances the capacity of the GB for absorbing radiation defects. Quite recently, Frolov et al [56] investigated the phase transitions of W [1 0 0] and [1 1 0] symmetric tilt GBs using the Universal Structure Predictor Evolutionary Xtallography (USPEX) structure prediction code and atomistic simulations, and observed the similar first-order GB phase transitions to that in Cu. The effect of the GB structural multiplicity on the mechanisms of V/SIA absorption was further investigated.…”

Section: Effect Of Radiation-defects On the Gb Structurementioning

confidence: 99%

Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

Zhang

et al. 2020

Tungsten

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As promising candidates for plasma-facing materials, tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux. Radiation-produced defects, e.g. selfinterstitial atoms (SIAs) and vacancies (Vs), can induce the hardening and embrittlement of tungsten, meanwhile enhancing the retention of hydrogen isotopes and helium in tungsten. Reducing the grain size of materials to introduce a high density of defect sinks, e.g., grain boundaries (GBs) prevalent in nano-/ultrafine-crystalline materials, was demonstrated to be an effective approach for mitigating irradiation damage in tungsten. In this paper, we reviewed the theoretical advances in exploring radiation-resistance of nano-structured tungsten at across scales. It was concentrated on the results of molecular dynamics, molecular statics, and the object kinetic Monte Carlo simulations on the fundamental interaction of the radiationcreated Vs and SIAs with the GB. These mechanisms include GB-promoted V/SIA migration and SIA-V recombination, interstitial-emission induced annihilation, coupling of the V migration close to the GB with the SIA motion within the GB, and interstitial reflection by the locally dense GB structure. We proposed the remaining scientific issues on the defect-GB interactions at across scales and their relation to experimental observations. We prospected the possible trends for simulating the radiation damage accumulation and healing processes in nano-structured tungsten in terms of the development of the across-scale computational techniques and efficiency of the GB-enhanced tolerance of tungsten to irradiation under complex in-service conditions.

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“…The GB microstructures observed in experiments and the corresponding GB properties actually reflect the temperature effects on GBs to some extent [ 3 , 34 ], because the change of temperature may lead to the transition of GB complexions, which is important to the properties of polycrystals [ 35 , 36 , 37 ]. The latest atomistic simulations reveal that there are several different metastable microstructures for the same GB and the further MD simulations showed that the stable structures at high temperature are related to these metastable structures for FCC [ 38 , 39 ] and BCC [ 40 , 41 ] metals. Recently, the coexistence of two different GB complexions in pure copper were observed experimentally [ 42 ], which gave the direct evidence for the transition of GB complexions in pure metals.…”

Section: Introductionmentioning

confidence: 99%

Survey of Grain Boundary Energies in Tungsten and Beta-Titanium at High Temperature

Wang

2021

Materials

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Heat treatment is a necessary means to obtain desired properties for most of the materials. Thus, the grain boundary (GB) phenomena observed in experiments actually reflect the GB behaviors at relatively high temperature to some extent. In this work, 405 different GBs were systematically constructed for body-centered cubic (BCC) metals and the grain boundary energies (GBEs) of these GBs were calculated with molecular dynamics for W at 2400 K and β-Ti at 1300 K and by means of molecular statics for Mo and W at 0 K. It was found that high temperature may result in the GB complexion transitions for some GBs, such as the Σ11{332}{332} of W. Moreover, the relationships between GBEs and sin(θ) can be described by the functions of the same type for different GB sets having the same misorientation axis, where θ is the angle between the misorientation axis and the GB plane. Generally, the GBs tend to have lower GBE when sin(θ) is equal to 0. However, the GB sets with the <110> misorientation axis have the lowest GBE when sin(θ) is close to 1. Another discovery is that the local hexagonal-close packed α phase is more likely to form at the GBs with the lattice misorientations of 38.9°/<110>, 50.5°/<110>, 59.0°/<110> and 60.0°/<111> for β-Ti at 1300 K.

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Structures and transitions in bcc tungsten grain boundaries and their role in the absorption of point defects

Cited by 53 publications

References 98 publications

Free energy of grain boundary phases: Atomistic calculations for Σ5(310)[001] grain boundary in Cu

Free energy of grain boundary phases: Atomistic calculations for Σ5(310)[001] grain boundary in Cu

Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

Survey of Grain Boundary Energies in Tungsten and Beta-Titanium at High Temperature

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