Vacancy formation energy in CuNiCo equimolar alloy and CuNiCoFe high entropy alloy: ab initio based study

Esfandiarpour, A.; Nasrabadi, M.N.

doi:10.1016/j.calphad.2019.101634

Cited by 16 publications

(7 citation statements)

References 19 publications

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“…As for the Pt vacancy, we calculated 8 approximately symmetrical sites (Figure S26B). The Pt vacancy formation energy was calculated as follow: where E v is the DFT calculated energy of the corresponding disordered Pt 3 Co bulk with a Pt vacancy, E Pt 3 Co is the energy of the perfect disordered Pt 3 Co bulk, and μ Pt is the chemical potential energy of Pt . And the Co vacancy formation energy could be defined as where μ Co is the chemical potential energy of Co and E Pt3Co is the total energy of Pt 3 Co. All possible results in Figure S27A indicate that the Co vacancy is easier to form in this disordered Pt 3 Co system.…”

Section: Methodsmentioning

confidence: 99%

“…8 approximately symmetrical sites (FigureS26B). The Pt vacancy formation energy was calculated as follow:where E v is the DFT calculated energy of the corresponding disordered Pt 3 Co bulk with a Pt vacancy, E Pt 3 Co is the energy of the perfect disordered Pt 3 Co bulk, and μ Pt is the chemical potential energy of Pt 63. And the Co vacancy formation energy could be defined as…”

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confidence: 99%

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Atomistic Imaging of Competition between Surface Diffusion and Phase Transition during the Intermetallic Formation of Faceted Particles

Fan

Zong

et al. 2021

ACS Nano

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To explore the ordering mechanism of facet alloy nanocrystals with randomly distributed atoms, we investigate kinetic and thermodynamic behaviors of the ordering phase transition from face-centered cubic Pt3Co nanocrystals to L12-Pt3Co intermetallic nanocrystals. It is observed that the ordering occurs from the surface and then gradually into the interior in a layer-by-layer mode, involving the competition between two kinds of phase transition modes: long-range surface diffusion-induced phase transition (SDIPT) and short-range reconstruction-induced body phase transition (RIBPT). The density functional theory calculations demonstrate that the surface status acts as a pivotal part in the thermodynamics and kinetics of the nanoscale ordering transition. With the development of the controllable heating process, both SDIPT and RIBPT modes can be manipulated as well as the morphology of the final product. This in situ work lays the foundations for potentially realizing shape-controlled intermetallic nanostructures by utilizing the thermal annealing method and makes preparations for the rational design of the surface and near-surface atomic configurations at the atomic scale.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Atomistic Imaging of Competition between Surface Diffusion and Phase Transition during the Intermetallic Formation of Faceted Particles

Fan

Zong

et al. 2021

ACS Nano

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Section: Introductionmentioning

confidence: 99%

“…While it is well known that refractory metals display high vacancy formation energies, in multi-principal element alloys bulk formation energies are often distributed across a wide energy range [ 43 , 44 , 45 , 46 ]. This introduces the possibility of energies significantly lower than the distribution averages [ 43 , 44 ], opening the door to enhanced vacancy-mediated behavior compared to pure refractory metals. Moreover, since vacancies are generally produced at material heterogeneities, it is of interest to investigate the differences between formation energy distributions in the bulk and at selected material defects such as dislocations, grain boundaries, and free surfaces.…”

Section: Introductionmentioning

confidence: 99%

Vacancy Energetics and Diffusivities in the Equiatomic Multielement Nb-Mo-Ta-W Alloy

Zhou

Marian

2022

Materials

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In this work, we study vacancy energetics in the equiatomic Nb-Mo-Ta-W alloy, especially vacancy formation and migration energies, using molecular statics calculations based on a spectral neighbor analysis potential specifically developed for Nb-Mo-Ta-W. We consider vacancy properties in bulk environments as well as near edge dislocation cores, including the effect of short-range order (SRO) by preparing supercells through Metropolis Monte-Carlo relaxations and temperature on the calculation. The nudged elastic band (NEB) method is applied to study vacancy migration energies. Our results show that both vacancy formation energies and vacancy migration energies are statistically distributed with a wide spread, on the order of 1.0 eV in some cases, and display a noticeable dependence on SRO. We find that, in some cases, vacancies can form with very low energies at edge dislocation cores, from which we hypothesize the formation of stable `superjogs’ on edge dislocation lines. Moreover, the large spread in vacancy formation energies results in an asymmetric thermal sampling of the formation energy distribution towards lower values. This gives rise to effective vacancy formation energies that are noticeably lower than the distribution averages. We study the effect that this phenomenon has on the vacancy diffusivity in the alloy and discuss the implications of our findings on the structural features of Nb-Mo-Ta-W.

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“…Vacancy formation energies for high-entropy alloys have been calculated for supercell setups using density functional theory [8][9][10][11][12][13][14] or were measured by positronannihilation spectroscopy (PAS) and dilatometry [15,16]. Calculations on the five component Cantor alloy (CoCr-FeMnNi) report vacancy formation energies from 1.93 eV to 2.19 eV [13,14], which are comparable to the experimental value of 1.7 eV determined by Sugita et al [16] using PAS.…”

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confidence: 99%

Thermodynamics of vacancies in concentrated solid solutions: From dilute Ni-alloys to the Cantor system

Utt,

Stukowski,

Albe

2021

Preprint

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The vacancy concentration at finite temperatures is studied for a series of (CoCrFeMn)1−x Ni Nix Ni alloys by grand-canonical Monte-Carlo (MC) simulations. The vacancy formation energies are calculated from a classical interatomic potential and exhibit a distribution due to the different chemical environments of the vacated sites. In dilute alloys, this distribution features multiple discrete peaks, while concentrated alloys exhibit an unimodal distribution as there are many different chemical environments of similar vacancy formation energy. MC simulations using a numerically efficient bond-counting model confirm that the vacancy concentration even in concentrated alloys may be calculated by the established Maxwell-Boltzmann equation weighted by the given distribution of formation energies. We calculate the variation of vacancy concentration as function of Ni content in the (CoCrFeMn)x Ni Ni1−x Ni and prove the excellent agreement of the thermodynamic model and the results from the grand-canonical Monte-Carlo simulations.

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Vacancy formation energy in CuNiCo equimolar alloy and CuNiCoFe high entropy alloy: ab initio based study

Cited by 16 publications

References 19 publications

Atomistic Imaging of Competition between Surface Diffusion and Phase Transition during the Intermetallic Formation of Faceted Particles

Atomistic Imaging of Competition between Surface Diffusion and Phase Transition during the Intermetallic Formation of Faceted Particles

Vacancy Energetics and Diffusivities in the Equiatomic Multielement Nb-Mo-Ta-W Alloy

Thermodynamics of vacancies in concentrated solid solutions: From dilute Ni-alloys to the Cantor system

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