Multiscale modeling of Radiation Induced Segregation in iron based alloys

Thuinet, Ludovic; Nastar, Maylise; Martínez, E.; Moladje, Gabriel Franck Bouobda; Legris, Alexandre; Soisson, Frédéric

doi:10.1016/j.commatsci.2018.03.024

Cited by 16 publications

(15 citation statements)

References 80 publications

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“…The RIS tendencies are inferred from the transport coefficients with the mean-field model derived by Nastar, Martinez et al [4,47] from Wiedersich's theory [89] and used in several following studies [34,44,45,6]. The solute concentration gradient next to defect sinks is related to the vacancy concentration gradient as [44]:…”

Section: Appendix D Radiation-induced Segregation Modelmentioning

confidence: 99%

“…A series of combined AKMC-phase field studies, based on an ab initio-fitted pair interaction model, has achieved a more accurate analysis of Cr segregation in FeCr, including the effects of flux coupling and nondilute concentrations [44,45,6]. The AKMC-computed PDC ratios are compared to the results of this work in Fig.…”

Section: Comparison With Previous Transport Coefficient Calculationsmentioning

confidence: 99%

“…Atomic diffusion controls also the microstructure evolution of irradiated materials driven by the permanent excess of point defects (PD). Due to the coupling between PD and atomic fluxes, solutes can migrate to PD sinks independently of thermodynamic driving forces, and cause radiation-induced segregation (RIS) on grain boundaries, dislocations, or any other features that may be present in the bulk structure [4,5,6]. This can catalyze solute clustering and be the precursor of phase precipitation.…”

Section: Introductionmentioning

confidence: 99%

“…However, the drawn conclusions on the RIS behavior disregarded the effects of flux coupling and predicted Ni depletion, in disagreement with the experimental evidence. The FeCr alloy has been the object of a series of studies based on rate-theory [43], atomistic kinetic Monte Carlo (AKMC) [44], and phase-field [45,6] models. They showed that SIA transport plays a crucial role and yields Cr enrichment at sinks in opposition to the vacancy-induced depletion.…”

Section: Introductionmentioning

confidence: 99%

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Solute diffusion by self-interstitial defects and radiation-induced segregation in ferritic Fe–X (X=Cr, Cu, Mn, Ni, P, Si) dilute alloys

et al. 2020

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This work investigates solute transport due to self-interstitial defects and radiation induced segregation tendencies in dilute ferritic alloys, by computing the transport coefficients of each system based on ab initio calculations of binding energies and migration rates. The implementation of the self-consistent mean field method in the KineCluE code allows to extend the calculation of transport coefficients to arbitrary interaction ranges, crystal structures, and diffusion mechanisms. The results show that the diffusivity of P, Mn, and Cr solute atoms is dominated by the dumbbell mechanism, that of Cu by vacancies, while the two mechanisms might be in competition for Ni and Si, despite the fact that the corresponding mixed dumbbells are not stable. Systematic enrichment at defect sinks is expected for P and Mn solutes due to dumbbell diffusion, and for Si due mainly to vacancy drag. Vacancy drag is also responsible for Cu and Ni enrichment below 1085 K. The RIS behavior of Cr is the outcome of a fine balance between dumbbell enrichment and vacancy depletion. Therefore, for dilute Cr concentrations global enrichment occurs below 540 K, and depletion above. This threshold temperature grows with solute concentration. The findings are in agreement with experimental observations of RIS and clustering phenomena, and confirm that solutedefect kinetic coupling plays an important role in the formation of solute clusters in reactor pressure vessel steels and other alloys.However, the capability of PDs (vacancies and self-interstitials) to carry solute atoms to the nucleation sites, although often inferred in simple terms from the solute-PD binding energies, is yet not fully characterized. Nowadays, precise analytical models based on the Self-Consistent Mean Field (SCMF) theory [25] or the Green-function approach [26], in combination with ab initio calculations of defect jump rates, allow for a highly accurate analysis of the intrinsic atomic-transport properties by calculation of the transport (Onsager) matrix [27]. By the latter methods, it has been proven that solute drag by vacancies is a widespread phenomenon arising below a given temperature threshold in body-centered cubic (bcc) [28,29], face-centered cubic (fcc) [30,31,32], and hexagonal close-packed (hcp) metals [33], provided that the vacancy-solute interaction is sufficiently strong.In dilute ferritic alloys, the threshold temperature has been systematically determined for all transition-metal impurities [34,29]. This threshold is near or above 1000 K for Cu, Mn, Ni, P, and Si, whereas it lies near 300 K for Cr. Therefore, vacancies are indeed capable of transporting all solutes to sinks (including nucleation sites), with the exception of Cr for which depletion at sinks is expected.On the other hand, the transport efficiency of self-interstitial atoms (SIA) has been only superficially investigated. Speculations based on ab initio evaluations of the stability of mixed dumbbells (MD) [35,36,37], and the interpretation of resistivity-recovery (RR) experiments [38,...

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Section: Appendix D Radiation-induced Segregation Modelmentioning

confidence: 99%

Section: Comparison With Previous Transport Coefficient Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solute diffusion by self-interstitial defects and radiation-induced segregation in ferritic Fe–X (X=Cr, Cu, Mn, Ni, P, Si) dilute alloys

et al. 2020

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“…Since a change in the chemical potentials affects only the cluster concentrations in Eq. 3, KineCluE is a crucial step in developing a general and efficient framework to provide accurate atomic-based kinetic properties for higher-scale models such as object kinetic Monte Carlo [58][59][60][61][62][63][64], cluster dynamics [65][66][67][68] or phasefield models [69][70][71].…”

Section: Cluster Transport Coefficientsmentioning

confidence: 99%

KineCluE: A kinetic cluster expansion code to compute transport coefficients beyond the dilute limit

Schuler

Messina

Nastar

2020

Computational Materials Science

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This paper introduces the KineCluE code that implements the self-consistent mean-field theory for clusters of finite size. Transport coefficients are obtained as a sum over cluster contributions (in a cluster expansion formalism), each being individually computed with KineCluE. This method allows for the calculation of these coefficients beyond the infinitely dilute limit, and is an important step in bridging the gap between dilute and concentrated approaches. Inside a finite volume of space containing the components of a given cluster, all kinetic trajectories are accounted for in an exact manner. The code, written in Python, adapts to a wide variety of systems, with various crystallographic structures (possibly under strain), defects and solute amount and types, and various jump mechanisms, including collective ones. The code also features a set of useful tools, such as the sensitivity study routine that allows for the identification of the most important jump frequencies to get accurate transport coefficients with minimum computational cost. PROGRAM SUMMARYProgram Title: KineCluE (KINEtic CLUster Expansion) Licensing provisions: LGPL Programming language: Python 3.6 Nature of problem: Providing a general method for computing transport coefficients from atomic jump frequencies, taking into account kinetic correlations.Solution method: The program relies on the selfconsistent mean field (SCMF) theory. The system is described in terms of lattice sites, defects and jump mechanisms. The first part of the code translates the diffusion problem for such system into an analytical linear eigenvalue problem. The second part of the code assigns numerical values to each analytical variable and then solves the linear problem.

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Phase Field Methods

Bellon¹,

Thuinet²

2020

Comprehensive Nuclear Materials

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Multiscale modeling of Radiation Induced Segregation in iron based alloys

Cited by 16 publications

References 80 publications

Solute diffusion by self-interstitial defects and radiation-induced segregation in ferritic Fe–X (X=Cr, Cu, Mn, Ni, P, Si) dilute alloys

Solute diffusion by self-interstitial defects and radiation-induced segregation in ferritic Fe–X (X=Cr, Cu, Mn, Ni, P, Si) dilute alloys

KineCluE: A kinetic cluster expansion code to compute transport coefficients beyond the dilute limit

Phase Field Methods

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