Density functional calculations of the formation and migration enthalpies of monovacancies in Ni: Comparison of local and nonlocal approaches

International audienceWe present a study of nickel-silicides ordered alloys by means of first-principles calculations. Emphasis was put on the phases (low and high temperatures) identified in the binary phase diagram, namely: Ni3Si-β1, -β2, and -β3, Ni31Si12-γ, Ni2Si-δ, -θ, Ni3Si2-ɛ, NiSi-MnP and NiSi2-α. In addition, some common structures are computed for information: L12, D03 and D022. The simulations reproduce with a high accuracy lattice parameters and formation energies of main experimental structures, except for β2 and β3. Our results clarify the crystallographic nature of the γ structure, and the comparison of experimental Raman spectra and vibrational calculations will help experimentalists to identify without ambiguity NiSi3 structures

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“…In the case of nickel, it has been shown that the DFT cohesive energy is overestimated by 0.1-0.3 eV (see the discussion Ref. [9]). …”

Section: Resultsmentioning

confidence: 97%

First-principles study of nickel-silicides ordered phases

Connétable

Thomas

2011

Journal of Alloys and Compounds

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“…54 Results in Ni compare well to other DFT calculations. 21,22,53,96,97 Eshelby corrections were found to be negligible except for the tetra-vacancy in Ni at −0.03 eV, the hexavacancy at −0.06 −0.03 and −0.05 eV in afmD Fe, afmI Fe and Ni, respectively, and the dumbbell at −0.05, −0.08 and −0.10 eV in afmD Fe, afmI Fe and Ni, respectively. The only non-negligible effect on binding energies was for the hexavacancy, where increases of 0.05, 0.03, and 0.03 eV apply in afmD Fe, afmI Fe and Ni, respectively.…”

Section: Solute Interactions With Point Defectsmentioning

confidence: 91%

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

et al. 2013

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An extensive set of first-principles density functional theory calculations have been performed to study the behavior of He, C, and N solutes in austenite, dilute Fe-Cr-Ni austenitic alloys, and Ni in order to investigate their influence on the microstructural evolution of austenitic steel alloys under irradiation. The results show that austenite behaves much like other face-centered cubic metals and like Ni in particular. Strong similarities were also observed between austenite and ferrite. We find that interstitial He is most stable in the tetrahedral site and migrates with a low barrier energy of between 0.1 and 0.2 eV. It binds strongly into clusters as well as overcoordinated lattice defects and forms highly stable He-vacancy (V m He n ) clusters. Interstitial He clusters of sufficient size were shown to be unstable to self-interstitial emission and VHe n cluster formation. The binding of additional He and V to existing V m He n clusters increases with cluster size, leading to unbounded growth and He bubble formation. Clusters with n/m around 1.3 were found to be most stable with a dissociation energy of 2.8 eV for He and V release. Substitutional He migrates via the dissociative mechanism in a thermal vacancy population but can migrate via the vacancy mechanism in irradiated environments as a stable V 2 He complex. Both C and N are most stable octahedrally and exhibit migration energies in the range from 1.3 to 1.6 eV. Interactions between pairs of these solutes are either repulsive or negligible. A vacancy can stably bind up to two C or N atoms with binding energies per solute atom up to 0.4 eV for C and up to 0.6 eV for N. Calculations in Ni, however, show that this may not result in vacancy trapping as VC and VN complexes can migrate cooperatively with barrier energies comparable to the isolated vacancy. This should also lead to enhanced C and N mobility in irradiated materials and may result in solute segregation to defect sinks. Binding to larger vacancy clusters is most stable near their surface and increases with cluster size. A binding energy of 0.1 eV was observed for both C and N to a [001] self-interstitial dumbbell and is likely to increase with cluster size. On this basis, we would expect that, once mobile, Cottrell atmospheres of C and N will develop around dislocations and grain boundaries in austenitic steel alloys.

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“…17 The reason for using the GGA method is that it uses some recent theoretical studies which showed higher accuracy than other approximations such as the local density approximation to calculate various properties of bulk nickel 18 or to calculate the formation and migration enthalpies of vacancies in nickel. 19 The plan-wave cut off energy was set as 400 eV for all calculations and 3 Â 3 Â 3 Â Monkhost-Pack 20 meshes were used to test the Brillouin zone in the reciprocal space, depending on the size of the studied unit cell. To determine the insertion energies of oxygen and vacancy formation energy in Ni, three different sizes (2 Â 2 Â 2, 3 Â 3 Â 3, and 4 Â 4 Â 2) of FCC (face-centered cubic) supercell having 32, 108, and 128 lattice sites were used to calculate the Ni and NiO bulk energy.…”

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confidence: 99%

First-principles study of interstitial diffusion of oxygen in nickel chromium binary alloy

Kim

Shin

Jung

et al. 2012

Applied Physics Letters

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The first-principles calculations of the diffusion processes of oxygen in pure Ni and Ni-Cr binary alloy are conducted to understand the oxidation behavior of nickel base alloys. The cohesive energy, insertion energy of atomic oxygen, and vacancy formation energy in nickel are calculated and compared with experimental data. The activation energies of oxygen are also calculated. The results show agreement with previous work for the oxygen diffusion in pure nickel. However, the calculated activation energy for the diffusion of oxygen in Ni-Cr binary alloy showed lower values than that in nickel because of the limitations of the current calculation model.

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Density functional calculations of the formation and migration enthalpies of monovacancies in Ni: Comparison of local and nonlocal approaches

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 48 publications

References 66 publications

First-principles study of nickel-silicides ordered phases

First-principles study of nickel-silicides ordered phases

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

First-principles study of interstitial diffusion of oxygen in nickel chromium binary alloy

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