Ab initio-based diffusion theory and tracer diffusion in Ni–Cr and Ni–Fe alloys

Tucker, Julie D.; Najafabadi, R.; Allen, Todd R.; Morgan, Dane

doi:10.1016/j.jnucmat.2010.08.003

Cited by 130 publications

(112 citation statements)

References 61 publications

(86 reference statements)

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“…In particular, we analyze the influence of the local environments on both vacancy and 100 dumbbell formation energies in fcc metals and dilute Fe-Cr-Ni alloys. 23,[33][34][35][36][37] The paper is organized as follows. Section II contains the computational details used to perform the DFT calculations.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

Piochaud¹,

Klaver²,

Adjanor³

et al. 2014

Phys. Rev. B

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The influence of the local environment on vacancy and self-interstitial formation energies has been investigated in a face-centered-cubic (fcc) Fe-10Ni-20Cr model alloy by analyzing an extensive set of first-principle calculations based on density functional theory. Chemical disorder has been considered by designing special quasirandom structures and four different collinear magnetic structures have been investigated in order to determine a relevant reference state to perform point defect calculations at 0 K. Two different convergence methods have also been used to characterize the importance of the method on the results. Although our fcc Fe-10Ni-20Cr would be better represented in terms of applications by the paramagnetic state, we found that the antiferromagnetic single-layer magnetic structure was the most stable at 0 K and we chose it as a reference state to determine the point defect properties. Point defects have been introduced in this reference state, i.e., vacancies and Fe-Fe, Fe-Ni, Fe-Cr, Cr-Cr, Ni-Ni, and Ni-Cr dumbbell interstitials oriented either parallel or perpendicular to the single layer antiferromagnetic planes. Each point defect studied was introduced at different lattice sites to consider a sufficient variety of local environments and analyze its influence on the formation energy values. We have estimated the point defect formation energies with linear regressions using variables which describe the local environment surrounding the point defects. The number and the position of Ni and Cr first nearest neighbors to the point defects were found to drive the evolution of the formation energies. In particular, Ni is found to decrease and Cr to increase the vacancy formation energy of the model alloy, while the opposite trends are found for the dumbbell interstitials. This study suggested that, to a first approximation, the first nearest atoms to point defects can provide reliable estimates of point defect formation energies.

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Section: Introductionmentioning

confidence: 99%

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

Piochaud¹,

Klaver²,

Adjanor³

et al. 2014

Phys. Rev. B

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“…Density functional theory (DFT) calculations have proven successful in predicting experimental data such as lattice parameters [46,47], elastic properties [48,49], and energy barriers for diffusion, e.g., diffusivities in aluminum [50], magnesium [51,52], and nickel [53]. Many impurity diffusivities in bcc iron [54][55][56][57][58][59][60][61] have been calculated with DFT methods, but oftentimes only experimentally fitted data, such as activation energy for diffusion, have been compared with the computed results. The fact that the Arrhenius plot of the diffusivity in bcc iron is not linear makes it desirable to compare the computed and experimentally determined diffusivities directly.…”

Section: Introductionmentioning

confidence: 99%

First-principles analysis of solute diffusion in dilute bcc Fe- X alloys

2017

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The diffusivities of substitutional impurity elements in iron have been computed with ab inito electronic density functional techniques, using exchange-correlation functional PW91. Excess entropies and the attempt frequency for a jump were determined by calculating phonon frequencies in the harmonic approximation. The influence of the degree of spontaneous magnetization on diffusivity is taken into account by means of the Girifalco model. The activation energy for diffusion has been determined by computing the vacancy formation energy, impurity-vacancy binding energies, migration barrier energies, and the effective energy associated with correlation of vacancy-mediated jump. For each type of impurity atom these contributions have been evaluated and analyzed up to and including the fifth nearest-neighbor shell of the impurity atom. It is found that impurities that have a low migration energy tend to have high effective energy associated with vacancy migration correlation, and vice versa, so that the total diffusion activation energies for all impurities are surprisingly close to each other. The strong effect of vacancy migration correlation is found to be associated with the high migration energy for iron self-diffusion, so that movement of vacancies through the iron bulk is in all cases, except cobalt, the limiting factor for impurity diffusion. The diffusivities calculated with the PW91 functional show good agreement with most of the experimental data for a wide range of elements.

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“…the free energy of the defects, must be considered. While some authors have pointed out the importance of considering full DFTbased free formation and migration energies of point defects at nonzero temperatures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] only few studies on the free energy of defect clusters have hitherto been published. The work of Yuge et al [18] is probably the only full DFT-based study which is exclusively related to the free energy of larger embedded defect clusters.…”

Section: Introductionmentioning

confidence: 99%

“…Such a method was also applied to calculate the free binding energy of vacancy-solute pairs in studies on the vacancy mechanism of solute diffusion in bcc Fe, fcc Al, and fcc Ni (Refs. [3,5,6,19]). In general one can expect that phonon and other excitations may have non-negligible effects on the total free binding energy of embedded defect clusters and on the free binding energy of point defects to these clusters, both of which are crucial input parameters of kinetic and Metropolis Monte Carlo simulations.…”

Section: Introductionmentioning

confidence: 99%