NSUF 19-1761: Alleviating irradiation-induced precipitation in a Fe-21Cr-5Al alloy via nanostructuring.
Due to their high strength and corrosion resistance in high temperature steam environments (>1000 oC), FeCrAl alloys are being considered as a replacement to zircaloy fuel cladding in commercial light water reactors (LWRs). One major drawback observed in high-Cr ferritic alloys in nuclear environments is the formation of Cr-rich α′ precipitates within the Fe-rich α-ferrite matrix. Understanding Cr-rich α′ precipitation is very important, as they contribute significantly to irradiation-induced hardening and embrittlement. Ultrafine grained (UFG) or nanocrystalline (NC) metals and alloys produced by equal channel angular pressing (ECAP) and high pressure torsion (HPT) possess an increased volume fraction of grain boundaries (GBs), contributing to increased strength by GB strengthening and enhanced irradiation tolerance due to the role of GBs as effective sinks for irradiation induced defects. It is thus presumed that nanostructured FeCrAl alloys will have enhanced resistance to α′ precipitation under irradiation conditions. High dose rate (>10-4 dpa/s) ion irradiation results in ballistic mixing becoming dominant over diffusion-induced precipitation, leading to the mitigation of α' formation in FeCrAl alloys. Accordingly, this study will only focus on low dose rate ion irradiations of nanostructured FeCrAl alloy to understand evolution of α′ as a function of dose and temperature, and also its dependence on grain sizes. However, there are no studies on ion irradiation of nanostructured FeCrAl alloy analyzing dependence of α′ precipitation on temperature, dose and grain size during ion irradiation. This proposed work will systematically study the dependence on dose, temperature, and grain size of α′ Cr precipitation to establish an understanding of the irradiation induced precipitation in nanostructured FeCrAl steels, which can lead to new strategies to alleviate irradiation-induced hardening and embrittlement. By establishing the irradiation performance of nanostructured FeCrAl steels with appealing properties directly impacts the life extension of current reactors and the development of advanced reactors. Hence, the proposed research is highly relevant to DOE-NE’s Accident Tolerant Fuel Campaign, Light Water Reactor Sustainability Program, and Advanced Fast Reactor Program. Conventionally processed CG, ECAP processed UFG, and HPT processed NC KD samples will be subjected to ion irradiation at different temperatures to different doses at constant dose rate of <10-4 dpa/s. The post irradiation examination (PIE) will involve microstructural characterization of the samples. Nanoindentation will also performed to correlate microstructural evolution to mechanical properties. The samples before irradiation (results already available) will be compared to samples after irradiation to understand microstructural evolution as a consequence of ion irradiation, with a focus on irradiation-induced segregation/precipitation.
Допълнителна информация
| Поле | Стойност |
|---|---|
| Abstract | Due to their high strength and corrosion resistance in high temperature steam environments (>1000 oC), FeCrAl alloys are being considered as a replacement to zircaloy fuel cladding in commercial light water reactors (LWRs). One major drawback observed in high-Cr ferritic alloys in nuclear environments is the formation of Cr-rich α′ precipitates within the Fe-rich α-ferrite matrix. Understanding Cr-rich α′ precipitation is very important, as they contribute significantly to irradiation-induced hardening and embrittlement. Ultrafine grained (UFG) or nanocrystalline (NC) metals and alloys produced by equal channel angular pressing (ECAP) and high pressure torsion (HPT) possess an increased volume fraction of grain boundaries (GBs), contributing to increased strength by GB strengthening and enhanced irradiation tolerance due to the role of GBs as effective sinks for irradiation induced defects. It is thus presumed that nanostructured FeCrAl alloys will have enhanced resistance to α′ precipitation under irradiation conditions. High dose rate (>10-4 dpa/s) ion irradiation results in ballistic mixing becoming dominant over diffusion-induced precipitation, leading to the mitigation of α' formation in FeCrAl alloys. Accordingly, this study will only focus on low dose rate ion irradiations of nanostructured FeCrAl alloy to understand evolution of α′ as a function of dose and temperature, and also its dependence on grain sizes. However, there are no studies on ion irradiation of nanostructured FeCrAl alloy analyzing dependence of α′ precipitation on temperature, dose and grain size during ion irradiation. This proposed work will systematically study the dependence on dose, temperature, and grain size of α′ Cr precipitation to establish an understanding of the irradiation induced precipitation in nanostructured FeCrAl steels, which can lead to new strategies to alleviate irradiation-induced hardening and embrittlement. By establishing the irradiation performance of nanostructured FeCrAl steels with appealing properties directly impacts the life extension of current reactors and the development of advanced reactors. Hence, the proposed research is highly relevant to DOE-NE’s Accident Tolerant Fuel Campaign, Light Water Reactor Sustainability Program, and Advanced Fast Reactor Program. Conventionally processed CG, ECAP processed UFG, and HPT processed NC KD samples will be subjected to ion irradiation at different temperatures to different doses at constant dose rate of <10-4 dpa/s. The post irradiation examination (PIE) will involve microstructural characterization of the samples. Nanoindentation will also performed to correlate microstructural evolution to mechanical properties. The samples before irradiation (results already available) will be compared to samples after irradiation to understand microstructural evolution as a consequence of ion irradiation, with a focus on irradiation-induced segregation/precipitation. |
| Award Announced Date | 2019-05-15T09:43:04.51 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Lin Shao, Yaqiao Wu |
| Irradiation Facility | Accelerator Laboratory |
| PI | Maalavan Arivu |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1761 |