Microstructural evolution of Fe 22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

Korchuganova, O. A.; Thuvander, Mattias; Aleev, A. A.; Рогожкин, С. В.; Boll, Torben; Kulevoy, T. V.

doi:10.1016/j.jnucmat.2016.05.007

Cited by 16 publications

(8 citation statements)

References 27 publications

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“…Likewise, Marquis et al [19] found no α' in Fe-15Cr irradiated by Fe ++ ions at a dose rate of 1×10 -4 dpa/s up to 60 dpa at 300 °C, but observed a small density clusters with only 35-50 at.% Cr in in a Fe-15Cr at a lower dose rate of ≈ 1×10 -5 dpa/s, suggesting a pronounced dose rate effect [19]. Korchuganova et al carried out a heavy-ion irradiation at room temperature on a Fe-22Cr alloy that was pre-aged at 500 °C to form α' precipitates with a distribution of sizes [20]. APT showed that the heavy-ion irradiation dissolved the small preexisting α' precipitates and made the larger ones more diffuse.…”

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confidence: 99%

Flux effects in precipitation under irradiation – Simulation of Fe-Cr alloys

Reese

Marquis

et al. 2019

Acta Materialia

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Radiation-enhanced precipitation of Cr-rich α' in irradiated Fe-Cr alloys, which results in hardening and embrittlement, depends on the irradiating particle and the displacement per atom (dpa) rate. Here, we utilize a Cahn-Hilliard phase-field based approach, that includes simple models for nucleation, irradiating particle and rate dependent radiation-enhanced diffusion and cascade mixing to simulate α' evolution under neutrons, heavy ions, and electron irradiations. Different irradiating particles manifest very different cascade mixing efficiencies. The model was calibrated using neutron data. For cascade inducing neutron/heavy-ion dpa rates at 300 °C between 10 -8 and 10 -6 dpa/s the model predicts approximately constant number density, decreasing radius, decreasing α' Cr composition, and lower α' volume fraction. The model then predicts a dramatic transition to no α'formation above approximately 10 -5 dpa/s, while electron irradiation, with weak mixing, had little effect at dpa rates up to 10 -3 dpa/s. These model predictions are consistent with experiments. We explain the results in terms of the flux dependence of the radiation enhanced diffusion, cascade mixing, and their ratio, which all vary significantly in relevant flux ranges for neutron and cascade inducing ion irradiations. These results show that both cascade mixing and radiation enhanced diffusion must be accounted for when attempting to emulate neutron-irradiation effects using accelerated ion irradiations. flux effects by triple-beam ions at 450 °C to 10 dpa [17]. Pareige et al. recently reported an APT study of Fe-12Cr under heavy-ion irradiation at 1×10 -4 dpa/s at 300 °C that observed a low density of dilute Cr clusters after irradiation to 0.5 dpa [18]. Likewise, Marquis et al. [19] found no α' in Fe-15Cr irradiated by Fe ++ ions at a dose rate of 1×10 -4 dpa/s up to 60 dpa at 300 °C, but observed a small density clusters with only 35-50 at.% Cr in in a Fe-15Cr at a lower dose rate of ≈ 1×10 -5 dpa/s, suggesting a pronounced dose rate effect [19]. Korchuganova et al. carried out a heavy-ion irradiation at room temperature on a Fe-22Cr alloy that was pre-aged at 500 °C to form α' precipitates with a distribution of sizes [20]. APT showed that the heavy-ion irradiation dissolved the small preexisting α' precipitates and made the larger ones more diffuse. A similar effect of heavy-ion irradiation was also shown to retard spinodal decomposition of Cr-rich α' in a duplex stainless steel with 20 wt.% Cr at 300 °C [21]. In contrast to the heavy-ion irradiation microstructures, Tissot et al. reported that a 3.9×10 -5 dpa/s electron irradiation at 300 °C accelerated precipitation of near equilibrium α' [22]. Accelerated α' precipitation under neutron irradiation has been attributed to radiation-enhanced diffusion (RED). RED depends on both temperature and dose rate due to the corresponding effect on vacancy and self-interstitial atom recombination mediated concentrations through a variety of mechanisms. However, a dose rate effect on RED does not full...

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Flux effects in precipitation under irradiation – Simulation of Fe-Cr alloys

Reese

Marquis

et al. 2019

Acta Materialia

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“…% хрома. Данное значение соответствует средней концентрации хрома в преципитатах из работы [Korchuganova et al, 2016]. На рис.…”

Section: энергии формирования вакансии в сплавахunclassified

“…На рис. 5 приведены полученные временные зависимости среднеквадратичного смещения атомов сплава для трех исследуемых моделей при 700 К. Температуры 900 К и выше не рассматривались в данной части исследования, поскольку при них уже проходит процесс гомогенизации данных сплавов [Korchuganova et al, 2016].…”

Section: диффузионная подвижность элементов сплавовunclassified

“…Стоит отметить, что в сплавах «железо-хром», с содержанием хрома выше 8-10 ат. %, под термическим воздействием и облучением могут формироваться обогащенные хромом преципитаты [Bonny et al, 2008;Svetukhin et al, 2013;Rogozhkin et al, 2013;Korchuganova et al, 2016], размер, компонентный состав и концентрация в объеме сплава которых может зависеть от степени этих воздействий [Korchuganova et al, 2016]. Данные образования также оказывают влияние на диффузионные подвижности точечных дефектов и элементов сплава.…”

Section: Introductionunclassified

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An analysis of interatomic potentials for vacancy diffusion simulation in concentrated Fe-Cr alloys

Svistunov¹,

Kolokol²

2018

CRM

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The study tested correctness of three interatomic potentials available in the scientific literature in reproducing a vacancy diffusion in concentrated Fe-Cr alloys by molecular dynamic simulations. It was necessary for further detailed study of vacancy diffusion mechanism in these alloys with Cr content 5-25 at. % at temperatures in the range of 600-1000 K. The analysis of the potentials was performed on alloys models with Cr content 10, 20, 50 at. %. The consideration of the model with chromium content 50 at. % was necessary for further study of diffusion processes in chromium-rich precipitates in these alloys. The formation energies and the atomic mobilities of iron and chromium atoms were calculated and analyzed in the alloys via an artificially created vacancy for all used potentials. A time dependence of mean squared displacement of atoms was chosen as а main characteristic for the analysis of atomic mobilities. The simulation of vacancy formation energies didn't show qualitative differences between the investigated potentials. The study of atomic mobilities showed a poor reproduction of vacancy diffusion in the simulated alloys by the concentration-dependent model (CDM), which strongly underestimated the mobility of chromium atoms via vacancy in the investigated range of temperature and chromium content. Also it was established, that the two-band model (2BM) of potentials in its original and modified version doesn't have such drawbacks. This allows one to use these potentials in simulations of vacancy diffusion mechanism in Fe-Cr alloys. Both potentials show a significant dependence of the ratio of chromium and iron atomic mobilities on temperature and Cr content in simulated alloys. The quantitative data of the diffusion coefficients of atoms obtained by these potentials also differ significantly.

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“…In the case of air‐quenched (AQ) samples, a small amount of dislocations disappear when the annealing temperature reaches 773 K, also, the Cr atoms aggregate at 900 K and dissolve at 1073 K . On this basis, the behavior of hydrogen, helium and other ions in Fe‐Cr model steels was studied using an ion‐irradiated sample …”

Section: Introductionmentioning

confidence: 99%

Evolution of Thermally‐Induced Microstructural Defects in the Fe‐9Cr Alloy

Lian

Cao

Zhao

et al. 2017

Physica Status Solidi (a)

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The purpose of the study detailed in this paper is to investigate the evolution of microstructural defects in the Fe‐9Cr binary alloy induced by isochronal annealing from 373 to 1223 K. Positron annihilation lifetime spectroscopy (PALS), Doppler broadening spectroscopy (DBS), positron annihilation lifetime calculation, and transmission electron microscope (TEM) are used to analyze and characterize the change of defect concentration, defect type and the micro‐morphology in the Fe‐9Cr alloy as a function of the annealing temperature. The experimental results showed that, a large number of vacancies and dislocations were found to exist in the untreated Fe‐9Cr alloy. The monovacancy (186.2 ps) in the Fe‐9Cr alloy migrated during annealing from room temperature to 573 K. The annealing temperature at 773 K produce aggregation of dislocations and the formation of dislocation networks, as well as their heterogeneous distribution. When the temperature is further increased to 1073 K, most of the vacancies and dislocations are recovered and a bcc‐fcc phase transmition occurred in Fe‐9Cr model alloy. The dislocation density is continuous decreased with the increase of annealing temperature, the recovery is obvious from 773 K annealing to 1073 K annealing in Fe‐9Cr alloy.

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Microstructural evolution of Fe 22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

Cited by 16 publications

References 27 publications

Flux effects in precipitation under irradiation – Simulation of Fe-Cr alloys

Flux effects in precipitation under irradiation – Simulation of Fe-Cr alloys

An analysis of interatomic potentials for vacancy diffusion simulation in concentrated Fe-Cr alloys

Evolution of Thermally‐Induced Microstructural Defects in the Fe‐9Cr Alloy

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