Modeling of radiation-induced segregation at grain boundaries in Fe–Cr–Ni alloys

Stepanov, I. A.; Pechenkin, V. A.; Konobeev, Yu. V.

doi:10.1016/j.jnucmat.2004.04.259

Cited by 20 publications

(18 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A function proportional to the square of the size factor, which could be motivated from elasticity arguments, does, however, give better agreement with the data. Overall, these results confirm the suggestions from experiment [1,2] and theory [4] that oversized solutes act as trapping sites for vacancies.…”

Section: Vacancy-solute Bindingsupporting

confidence: 89%

“…However, the instability of vac 4 -Y (and probably of vac 6 -Y) mean that the oversized solutes do act as nucleation sites for large voids. This explains why oversized defects lead to many small voids rather than few large ones.…”

Section: Vacancy Clustering and Void Nucleationmentioning

confidence: 99%

“…Stepanov et al [4] demonstrated that a model based on the trapping of vacancies by oversized solutes was capable of reproducing the simultaneous suppression of RIS and void swelling observed experimentally. The primary aim of the current work is to improve upon the theoretical understanding of the mechanisms underpinning the experimental observations of Kato et al [1,2] using detailed first-principles calculations of the atomic-level processes involved.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transition metal solute interactions with point defects in fcc iron from first principles

2015

View full text Add to dashboard Cite

We present a comprehensive set of first-principles electronic structure calculations of the properties of substitutional transition metal solutes and point defects in austenite (face-centered cubic, paramagnetic Fe). Clear trends were observed in these quantities across the transition metal series, with solute-defect interactions strongly related to atomic size, and only weakly related to more subtle details of magnetic or electronic structure. Oversized solutes act as strong traps for both vacancy and self-interstitial defects and as nucleation sites for the development of protovoids and small self-interstitial loops. The consequent reduction in defect mobility and net defect concentrations in the matrix explains the observation of reduced swelling and radiation-induced segregation. Our analysis of vacancy-mediated solute diffusion demonstrates that below about 400 K Ni and Co will be dragged by vacancies and their concentrations should be enhanced at defect sinks. Cr and Cu show opposite behavior and are depleted at defect sinks. The stable configuration of some oversized solutes is neither interstitial nor substitutional; rather they occupy two adjacent lattice sites. The diffusion of these solutes proceeds by a novel mechanism, which has important implications for the nucleation and growth of complex oxide nanoparticles contained in oxide dispersion strengthened steels. Interstitial-mediated solute diffusion is negligible for all except the magnetic solutes (Cr, Mn, Co, and Ni). Our results are consistent across several antiferromagnetic states and surprising qualitative similarities with ferromagnetic (body-centered cubic) Fe were observed; this implies that our conclusions will be valid for paramagnetic iron.

show abstract

Section: Vacancy-solute Bindingsupporting

confidence: 89%

Section: Vacancy Clustering and Void Nucleationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transition metal solute interactions with point defects in fcc iron from first principles

2015

View full text Add to dashboard Cite

show abstract

“…65-68 Kato 66,68 suggested the positive binding of vacancies to the relatively immobile oversized solutes as a mechanism by enhancing recombination and inhibiting vacancy diffusion, which is supported by the modeling of Stepanov 69 in the case of RIS. The vacancy-Ni binding observed in this work is small but is likely to be cumulative and should therefore not be overlooked as a contributory mechanism for void suppression at higher Ni concentrations.…”

Section: A Defect-solute Interactionmentioning

confidence: 92%

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

2012

View full text Add to dashboard Cite

We present results of an extensive set of first-principles density functional theory calculations of point defect formation, binding, and clustering energies in austenitic Fe with dilute concentrations of Cr and Ni solutes. A large number of possible collinear magnetic structures were investigated as appropriate reference states for austenite. We found that the antiferromagnetic single-and double-layer structures with tetragonal relaxation of the unit cell were the most suitable reference states and highlighted the inherent instabilities in the ferromagnetic states. Test calculations for the presence and influence of noncollinear magnetism were performed but proved mostly negative. We calculate the vacancy formation energy to be between 1.8 and 1.95 eV. Vacancy cluster binding was initially weak at 0.1 eV for divacancies but rapidly increased with additional vacancies. Clusters of up to six vacancies were studied and a highly stable octahedral cluster and stacking fault tetrahedron were found with total binding energies of 2.5 and 2.3 eV, respectively. The 100 dumbbell was found to be the most stable self-interstitial with a formation energy of between 3.2 and 3.6 eV and was found to form strongly bound clusters, consistent with other fcc metals. Pair interaction models were found to be capable of capturing the trends in the defect cluster binding energy data. Solute-solute interactions were found to be weak in general, with a maximal positive binding of 0.1 eV found for Ni-Ni pairs and maximum repulsion found for Cr-Cr pairs of −0.1 eV. Solute cluster binding was found to be consistent with a pair interaction model, with Ni-rich clusters being the most stable. Solute-defect interactions were consistent with Ni and Cr being modestly oversized and undersized solutes, respectively, which is exactly opposite to the experimentally derived size factors for Ni and Cr solutes in type 316 stainless steel and in the pure materials. Ni was found to bind to the vacancy and to the 100 dumbbell in the tensile site by 0.1 eV and was repelled from mixed and compressive sites. In contrast, Cr showed a preferential binding to interstitials. Calculation of tracer diffusion coefficients found that Ni diffuses significantly more slowly than both Cr and Fe, which is consistent with the standard mechanism used to explain radiation-induced segregation effects in Fe-Cr-Ni austenitic alloys by vacancy-mediated diffusion. Comparison of our results with those for bcc Fe showed strong similarity for pure Fe and no correlation with dilute Ni and Cr.

show abstract

“…Radiation induced segregation of Cr, Ni, Si and P at the grain boundary of a 300 series stainless steel irradiated in a light water reactor core to several dpa at 300°C [2]. While observations of RIS in Fe-Cr-Ni alloys are adequately explained by a vacancy diffusion mechanism, Watanabe et al [13] and Stepanov et al [14] have proposed that in fact, RIS at low temperature can only be explained by the binding of Ni atoms to interstitials with a binding energy of 0.75 eV. Experimental verification is through electron irradiation at high dose rates and low temperatures.…”

Section: Summary Of Current State Of Knowledge Of Ris In Fe-and Ni-bamentioning

confidence: 99%

Assessment of radiation-induced segregation mechanisms in austenitic and ferritic–martensitic alloys

Was

Wharry

Frisbie

et al. 2011

Journal of Nuclear Materials

134

View full text Add to dashboard Cite

Modeling of radiation-induced segregation at grain boundaries in Fe–Cr–Ni alloys

Cited by 20 publications

References 8 publications

Transition metal solute interactions with point defects in fcc iron from first principles

Transition metal solute interactions with point defects in fcc iron from first principles

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

Assessment of radiation-induced segregation mechanisms in austenitic and ferritic–martensitic alloys

Contact Info

Product

Resources

About