Characterisation of interfacial segregation to Cu-enriched precipitates in two thermally aged reactor pressure vessel steel welds

Styman, Paul; Hyde, J.M.; Wilford, K.; Parfitt, David; Riddle, Nick; Smith, George Davey

doi:10.1016/j.ultramic.2015.05.013

Cited by 32 publications

(20 citation statements)

References 30 publications

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“…Previous thermodynamic models suggested that in addition to enriching the Cu core, solutes such as Mn, Ni and Si form a surrounding shell due to reduction of the high interfacial energy between Fe and Cu [18]. Such core-shell structures were subsequently widely reported in APT studies, both under irradiation and thermal aging conditions [16,[19][20][21]. More recently, APT showed that at longer times (or higher irradiation fluence) after Cu in matrix is depleted, and when more Mn, Ni and Si atoms come out of solution, the core-shell structure gives way to a Cu-core-MnNiSi-appendage co-precipitate morphology.…”

Section: Introductionmentioning

confidence: 94%

“…By coupling recent advances in near-atomic resolution characterization techniques in three dimensions, such as atom probe tomography (APT) [11,12], with atomistic simulation tools such as kinetic lattice Monte Carlo (KLMC) [13], it is possible to study the precipitation pathways of multicomponent alloys in a quantitative manner. Here, we use these techniques to model the pathway of Cu-MnNiSi co-precipitation observed in irradiated (and thermally aged) Cu-bearing low-alloy steels [14][15][16]. Specifically, we focus on the mechanism of a transition of the coprecipitate from a Cu-core-MnNiSi-shell structure to a Cu-core-MnNiSi-appendage structure.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermodynamics and kinetics of core-shell versus appendage co-precipitation morphologies: An example in the Fe-Cu-Mn-Ni-Si system

Shu¹,

Wells²,

Almirall³

et al. 2018

Acta Materialia

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What determines precipitate morphologies in co-precipitating alloy systems? We focus on alloys of two precipitating phases, with the fast-precipitating phase acting as heterogeneous nucleation sites for a second phase manifesting slower kinetics. Kinetic lattice Monte Carlo simulations show that the interplay between interfacial and ordering energies, plus active diffusion paths, strongly affect the selection of core-shell verses appendage morphologies. We study a FeCuMnNiSi alloy using the combination of atom probe tomography and simulations, and show that the ordering energy reduction of the MnNiSi phase heterogeneously nucleated on a pre-existing copper-rich precipitate exceeds the energy penalty of a predominantly Fe/Cu interface, leading to initial appendage, rather than core-shell, formation. Diffusion of Mn, Ni and Si around and through the Cu core towards the ordered phase results in subsequent appendage growth. We further show that in cases with higher primary precipitate interface energies and/or suppressed ordering, the coreshell morphology is favored.3

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Thermodynamics and kinetics of core-shell versus appendage co-precipitation morphologies: An example in the Fe-Cu-Mn-Ni-Si system

Shu¹,

Wells²,

Almirall³

et al. 2018

Acta Materialia

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show abstract

“…The latter result has been confirmed on RPV steels (e.g., [58]). -Long term aging (up to 100,000 hours) at 330°C on high Cu steels (Cu > 0.4 wt%) leads to the formation of Cu-rich precipitates made of a Cu-rich core surrounded by a shell of Mn, Ni and Si atoms, very similar to clusters obtained after neutron irradiation [134,135].…”

Section: Hardening Defectsmentioning

confidence: 68%

“…More specifically, several analyses showed that Ni, Mn, and Si reduce the interface energy of Cu clusters in Fe (e.g., [85,135]), which supports the formation of Ni, Mn, and Si shells around Cu-rich cores.…”

Section: Hardening Defectsmentioning

confidence: 95%

60th Anniversary of electricity production from light water reactors: Historical review of the contribution of materials science to the safety of the pressure vessel

Duysen

Bellefon

2017

Journal of Nuclear Materials

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The first light water nuclear reactor dedicated to electricity production was commissioned in Shippingport, Pennsylvania in the United States in 1957. Sixty years after the event, it is clear that this type of reactor will be a major source of electricity and one of the key solutions to limit climate change in the 21 st century. This article pays homage to the teams that contributed to this achievement by their involvement in research and development and their determination to push back the frontiers of knowledge. Via a few examples of scientific or technological milestones, it describes the evolution of ideas, models, and techniques during the last 60 years, and gives the current state-of-the-art in areas related to the safety of the reactor pressure vessel. Among other topics, it focuses on vessel manufacturing, steel fracture mechanics analysis, and understanding of irradiation-induced damage.

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“…The Cu content in modern Grade 3 A508 RPV steels is low (typically < 0.1 at %), and Cu phase separates early in the lifetime of the reactor (<10 23 n m -2 fluence, ≥1 MeV) [69]. Due to the established flux-coupling effect of vacancy drag of Ni, Mn and Si to existing Cu clusters [3,27,70] and the strong binding energy (-0.2 eV) of Cu-Ni-Mn triplets, existing Cu clusters will act locally as nucleation points for Mn-Ni clusters, evidence for this is seen experimentally with the observation of Cu-rich cores surrounded by Mn-Ni-Si rich shells [5,[36][37][38]71]. The availability of Si (0.2 -0.6 at.…”

Section: Mn-ni Tripletsmentioning

confidence: 96%

Understanding the importance of the energetics of Mn, Ni, Cu, Si and vacancy triplet clusters in bcc Fe

Whiting

Burr

King

et al. 2019

Journal of Applied Physics

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Numerous experimental studies have found the presence of (Cu)-Ni-Mn-Si clusters in neutron irradiated reactor pressure vessel steels, prompting concerns that these clusters could lead to larger than expected increases in hardening, especially at high fluences late in life. The mechanics governing clustering for the Fe-Mn-Ni-Si system are not well-known; state-of-the-art methods use kinetic Monte Carlo (KMC) parameterised by density functional theory (DFT) and thermodynamic data to model the time evolution of clusters. However, DFT based KMC studies have so far been limited to only pairwise interactions due to lack of DFT data. Here we explicitly calculate the binding energy of triplet clusters of Mn, Ni, Cu, Si and vacancies in bcc Fe using DFT to show that the presence of vacancies, Si, or Cu stabilises cluster formation, as clusters containing exclusively Mn and/or Ni are not energetically stable in the absence of interstitials. We further identify which clusters may be reasonably approximated as a sum of pairwise interactions, and which instead require an explicit treatment of the three-body interaction, showing that the three-body term can account for as much as 0.3 eV, especially for clusters containing vacancies.

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Characterisation of interfacial segregation to Cu-enriched precipitates in two thermally aged reactor pressure vessel steel welds

Cited by 32 publications

References 30 publications

Thermodynamics and kinetics of core-shell versus appendage co-precipitation morphologies: An example in the Fe-Cu-Mn-Ni-Si system

Thermodynamics and kinetics of core-shell versus appendage co-precipitation morphologies: An example in the Fe-Cu-Mn-Ni-Si system

60th Anniversary of electricity production from light water reactors: Historical review of the contribution of materials science to the safety of the pressure vessel

Understanding the importance of the energetics of Mn, Ni, Cu, Si and vacancy triplet clusters in bcc Fe

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