First-principles study of bismuth films at transition-metal grain boundaries

Gao, Qin; Widom, Michael

doi:10.1103/physrevb.90.144102

Cited by 17 publications

(20 citation statements)

References 41 publications

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“…and adsorption (Γ) vs. bulk composition (X Bulk ) curves for Bi-doped Ni at three different temperatures. Here, γ GB (0) is computed to be~1.26 J/m 2 for the average general GBs in pure Ni, which is consistent with experiments (~1 J/m 2 ) and DFT calculations (1.2-1.4 J/m 2 ) [30,35,36]. At each temperature, the GB undergoes a first-order phase-like (complexion) transformation with increasing bulk composition, from a "clean" GB to a bilayer; here, both the "clean" GB and the bilayer are nominal as the actual GB excess (Γ), which varies with the chemical potential, is around the nominal value of 0 or 2 monolayer(s) (Fig.…”

Section: Contents Lists Available At Sciencedirectsupporting

confidence: 63%

“…Fig. 2 (a) and (b) compare the (γ GB − γ GB (0) ) vs. chemical potential difference curves for two twist "general" GBs calculated using the lattice model and CALPHAD data with two independent DFT calculations [30,31] for two Σ5 tilt and one Σ3 twist GBs at T = 0 K. There are several differences between the lattice model and DFT calculations. First, the relaxed bilayer structures obtained by DFT is less dense (with reconstructions) than that of the lattice model and the effective regular-solution parameter at the GB can be different (negative) due to the relaxation of the positive strain energy, which further stabilizes bilayers.…”

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confidence: 99%

“…They do not consider possible structural changes at GBs (by placing all atoms on the lattice) and rely on empirical parameters. Thus, we further compare this model with two prior DFT calculations [30,31] that consider the detailed atomic structures (for selected special GBs at T = 0 K). Fig.…”

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confidence: 99%

“…Furthermore, we calculated the GB transition lines for two special GBs based on the 0 K density functional theory (DFT) calculations reported in two prior studies [30,31] for Scripta Materialia 130 (2017) [165][166][167][168][169] …”

Section: Abstract a R T I C L E I N F Omentioning

confidence: 99%

“…Third, the Bi chemical potentials in the NiBi compound obtained from the CALPHAD and DFT are somewhat different (noting that the CALPHAD data were fitted referencing to the bulk compound so that the relative chemical potentials are likely more relevant). Finally, the lattice model is designed to represent the average general (Σ ∞) GBs, whereas DFT calculations were conducted for special Σ5 tilt GBs and for the lowest-energy Σ3 (111) twist GB [29][30][31]. Nonetheless, it is interesting to note that the relative stabilities of the "clean" vs. bilayer complexions at the average general GBs represented the lattice model are between the two DFT calculations for Σ5 (210) and Σ5 (310) tilt GBs [30,31] (Fig.…”

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confidence: 99%

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Calculation and validation of a grain boundary complexion diagram for Bi-doped Ni

Zhou

Zhang

et al. 2017

Scripta Materialia

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a b s t r a c t a r t i c l e i n f oA grain boundary (GB) "phase" (complexion) diagram is computed via a lattice type statistical thermodynamic model for the average general GBs in Bi-doped Ni. The predictions are calibrated with previously-reported density functional theory calculations and further validated by experiments, including both new and old aberrationcorrected scanning transmission electron microscopy characterization results as well as prior Auger electron spectroscopy measurements. This work supports a major scientific goal of developing GB complexion diagrams as an extension to bulk phase diagrams and a useful materials science tool.© 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Grain boundaries (GBs) can undergo phase-like transformations, for example, premelting [1] or adsorption [2] transitions, which can influence a broad range of materials properties [3][4][5]. Thus, GBs can be treated as "interfacial phases" that are thermodynamically two-dimensional (2-D) despite that they have thermodynamically-determined interfacial widths as well as through-thickness compositional and structural gradients. A new term "complexion" was introduced to differentiate such 2-D interfacial phases from the conventional bulk phases defined by Gibbs [1,3,4,6,7].Phase diagrams are one of the most useful tools for materials engineering. Materials scientists have long recognized that phase-like behaviors at GBs can often control the fabrication processing, microstructural evolution, and materials properties [3,[6][7][8][9][10][11][12]. Thus, a potentially-transformative research is represented by the development of GB "phase" (a.k.a. complexion) diagrams as an extension to bulk phase diagrams and a generally-useful materials science tool. To support this goal, recent studies [9,10,13-16] have extended bulk CALPHAD (CALculation of PHAse Diagrams) methods to model coupled GB premelting and prewetting (a.k.a. the formation of nanoscale, impurity-based, quasi-liquid complexions) and subsequently constructed a class of "GB λ diagrams" to represent the thermodynamic tendency for general GBs to disorder at high temperatures. Although the predicted trends have been validated with direct high-resolution transmission electron microscopy (HRTEM) [9,[14][15][16][17][18][19] and proven useful for forecasting sintering behaviors [9,10,[13][14][15]20], these GB λ diagrams are not yet rigorous GB complexion diagrams with well-defined transition lines. An early report in 1999 [21] also constructed a GB complexion diagram for Cu-Bi via a rather simple model that considered GBs as "quasi-liquid layers" to explain the GB segregation behaviors measured by Auger electron spectroscopy (AES), but more recent aberration-corrected scanning transmission electron microscopy (AC STEM) observed an ordered bilayer complexion in Cu-Bi instead [22]. GB complexion diagrams with first-order transition lines and critical points have been constructed using diffuse-interface (phase-field) [1,23,24] and latticetype [16,[25][26]...

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Section: Contents Lists Available At Sciencedirectsupporting

confidence: 63%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

Section: Abstract a R T I C L E I N F Omentioning

confidence: 99%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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Calculation and validation of a grain boundary complexion diagram for Bi-doped Ni

Zhou

Zhang

et al. 2017

Scripta Materialia

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Role of grain boundary character on oxygen and hydrogen segregation-induced embrittlement in polycrystalline Ni

Chen

Dongare

2016

J Mater Sci

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

et al. 2018

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We use atomistic simulations to investigate grain boundary (GB) phase transitions in elemental body-centered cubic (bcc) metal tungsten. Motivated by recent modeling study of grain boundary phase transitions in [100] symmetric tilt boundaries in face-centered cubic (fcc) copper, we perform a systematic investigation of [100] and [110] symmetric tilt high-angle and low-angle boundaries in bcc tungsten. The structures of these boundaries have been investigated previously by atomistic simulations in several different bcc metals including tungsten using the the γ-surface method, which has limitations. In this work we use a recently developed computational tool based on the USPEX structure prediction code to perform an evolutionary grand canonical search of GB structure at 0 K. For high-angle [100] tilt boundaries the ground states generated by the evolutionary algorithm agree with the predictions of the γ-surface method. For the [110] tilt boundaries, the search predicts novel high-density low-energy grain boundary structures and multiple grain boundary phases within the entire misorientation range. Molecular dynamics simulation demonstrate that the new structures are more stable at high temperature. We observe first-order grain boundary phase transitions and investigate how the structural multiplicity affects the mechanisms of the point defect absorption. Specifically, we demonstrate a two-step nucleation process, when initially the point defects are absorbed through a formation of a metastable GB structure with higher density, followed by a transformation of this structure into a GB interstitial loop or a different GB phase.

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First-principles study of bismuth films at transition-metal grain boundaries

Cited by 17 publications

References 41 publications

Calculation and validation of a grain boundary complexion diagram for Bi-doped Ni

Calculation and validation of a grain boundary complexion diagram for Bi-doped Ni

Role of grain boundary character on oxygen and hydrogen segregation-induced embrittlement in polycrystalline Ni

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

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