Dose rate dependence of Cr precipitation in an ion-irradiated Fe 18Cr alloy

Reese, Elaina R.; Almirall, Nathan; Yamamoto, Takuya; Tumey, Scott J.; Odette, G.R.; Marquis, Emmanuelle A.

doi:10.1016/j.scriptamat.2017.11.040

Cited by 65 publications

(22 citation statements)

References 29 publications

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“…Similar phemonema happened to the α precipitates in ion-irradiated BCC Fe-Cr alloys. The Cr concentation of the α precipitates is below equilibrium in lower dose-rate ion irradiated Fe-18Cr [42] and no α precipitates could be found in high dose-rate ( 10 −3 dpa/s) ion-irradiated Fe-Cr alloys. Similar Ni and Si segragation and Ni,Si-rich precipitates have also been observed in irradiated 316H.…”

Section: Radiation-induced Segregation and Precipitationmentioning

confidence: 87%

“…Recent studies have shown that the α precpitation is a radiation-enhanced process [38][39][40][41][42], and the α precpitates could be influenced by the cascade damage during irradiation [42]. A previous study on electron-irradiated Fe-15Cr has shown that without cascade damage, radiation greatly enhanced the α precipitation process (shown in Fig.…”

Section: Radiation Effects In Ferritic/martensitic Alloysmentioning

confidence: 96%

“…In fact, many heavy ion irradiation studies using high dose rates ( 10 −3 dpa/s) failed to find any α precipitates in irradiated Fe-Cr alloys. Only recently, a study employing low dose rates (10 −5 -10 −4 dpa/s) heavy ion irradiation observed α precipitates [42] with compositions much lower than phase diagram predictions [42].…”

Section: Radiation Effects In Ferritic/martensitic Alloysmentioning

confidence: 99%

See 2 more Smart Citations

Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys

Stubbins

Heuser

Hosemann

et al. 2018

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Section: Radiation-induced Segregation and Precipitationmentioning

confidence: 87%

Section: Radiation Effects In Ferritic/martensitic Alloysmentioning

confidence: 96%

Section: Radiation Effects In Ferritic/martensitic Alloysmentioning

confidence: 99%

See 1 more Smart Citation

Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys

Stubbins

Heuser

Hosemann

et al. 2018

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“…[9] and Reese et al [81,96] who observed precipitation in 9 to 18Cr alloys over a range of temperatures, including the neutron irradiations at 320 °C used to calibrate the model, in a dose rate regime minimally affected by cascade mixing. However, the updated thermodynamic parameterization for the Fe-Cr system does not provide adequate kinetics of nucleation and growth of α' in Fe-12Cr, contrary to observation.…”

Section: Potential Applications Limitations and Insights Of The Modelmentioning

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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“…Reese et al . 33 observing non-equilibrium α′ concentrations as a result of heavy ion irradiations concluded that dpa rate and the ballistic mixing are the factors to effect the α′ and their concentration.…”

Section: Introductionmentioning

confidence: 99%

α′ formation kinetics and radiation induced segregation in neutron irradiated 14YWT nanostructured ferritic alloys

Aydoğan

Saez

March

et al. 2019

Sci Rep

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Nanostructured ferritic alloys are considered as candidates for structural components in advanced nuclear reactors due to a high density of nano-oxides (NOs) and ultrafine grain sizes. However, bimodal grain size distribution results in inhomogeneous NO distribution, or vice versa. Here, we report that density of NOs in small grains (<0.5 µm) is high while there are almost no NOs inside the large grains (>2 µm) before and after irradiation. After 6 dpa neutron irradiation at 385–430 °C, α′ precipitation has been observed in these alloys; however, their size and number densities vary considerably in small and large grains. In this study, we have investigated the precipitation kinetics of α′ particles based on the sink density, using both transmission electron microscopy and kinetic Monte Carlo simulations. It has been found that in the presence of a low sink density, α′ particles form and grow faster due to the existence of a larger defect density in the matrix. On the other hand, while α′ particles form far away from the sink interface when the sink size is small, Cr starts to segregate at the sink interface with the increase in the sink size. Additionally, grain boundary characteristics are found to determine the radiation-induced segregation of Cr.

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Dose rate dependence of Cr precipitation in an ion-irradiated Fe 18Cr alloy

Cited by 65 publications

References 29 publications

Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys

Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys

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

α′ formation kinetics and radiation induced segregation in neutron irradiated 14YWT nanostructured ferritic alloys

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