NSUF 16-710: Modeling nanocluster evolution in irradiated ferritic ODS and ferritic/martensitic alloys
The objective of this project is to provide validation data for a computational model of nanocluster stability in irradiated b.c.c. Fe-based alloys. Ferritic/martensitic (F/M) and oxide dispersion strengthened (ODS) alloys offer high strength and dimensional stability upon irradiation, making them leading candidates for structural and fuel cladding applications for advanced nuclear reactor designs. Their high sink strengths provide resistance to irradiation-induced swelling and embrittlement. As such, it is critical to have a clear understanding of how the microstructures of these alloys will evolve with long-term irradiation. To date, studies evaluating the stability of Y-Ti-O-rich nanoclusters in ODS alloys have shown either coarsening or dissolution, depending on the alloy and irradiation conditions. Meanwhile, F/M alloys have exhibited variable irradiation-induced nucleation of Si-Mn-Ni-Cu and Cr-rich nanoclusters. With such inconclusive results, a methodology for predicting irradiation-induced evolution of nanoclusters is needed to assist the development of nanofeatured alloys for irradiation resistance. We have advanced a calculation method to predict cluster evolution in b.c.c. Fe-based alloys, but more data points are required to fully validate the model.
Thus far, our model is benchmarked against cluster data from proton- and neutron-irradiated ODS and F/M specimens irradiated to 3 dpa at 500°C. After both irradiations, Fe-9%Cr ODS exhibited partial dissolution of the Y-Ti-O nanoclusters resulting in a bimodal size distribution. Meanwhile, F/M alloys HCM12A and HT9 exhibit two types of irradiation-induced nanoclusters: Si-Mn-Ni-Cu clusters, and Cr-rich clusters to various degrees of coarsening. Although the model is capable of predicting each of these various results, additional data to establish the nucleation threshold and evolution rate of clusters will make the model more robust and applicable to other irradiation conditions (e.g. neutrons, self-ions) and alloys, making the model more versatile.
This project will focus on the same Fe-9%Cr ODS, HCM12A and HT9 alloys, each irradiated with 2.0 MeV protons to 1 dpa and 7 dpa at 500°C. Characterization of samples irradiated to 1 dpa will elucidate the nucleation rate and evolution rate of new clusters, while characterization of 7 dpa specimens will confirm the long-term cluster stability of the bimodal size distribution of Y-Ti-O clusters in the ODS alloy.
The project will enable validation of the Nelson, et al. approach as a viable model of cluster evolution in irradiated b.c.c. Fe-based alloys, providing a valuable technique to assist nanofeatured alloy development, which are of growing interest to the Department of Energy Office of Nuclear Energy, due to their enhanced radiation resistance.
Additional Info
| Field | Value |
|---|---|
| Abstract | The objective of this project is to provide validation data for a computational model of nanocluster stability in irradiated b.c.c. Fe-based alloys. Ferritic/martensitic (F/M) and oxide dispersion strengthened (ODS) alloys offer high strength and dimensional stability upon irradiation, making them leading candidates for structural and fuel cladding applications for advanced nuclear reactor designs. Their high sink strengths provide resistance to irradiation-induced swelling and embrittlement. As such, it is critical to have a clear understanding of how the microstructures of these alloys will evolve with long-term irradiation. To date, studies evaluating the stability of Y-Ti-O-rich nanoclusters in ODS alloys have shown either coarsening or dissolution, depending on the alloy and irradiation conditions. Meanwhile, F/M alloys have exhibited variable irradiation-induced nucleation of Si-Mn-Ni-Cu and Cr-rich nanoclusters. With such inconclusive results, a methodology for predicting irradiation-induced evolution of nanoclusters is needed to assist the development of nanofeatured alloys for irradiation resistance. We have advanced a calculation method to predict cluster evolution in b.c.c. Fe-based alloys, but more data points are required to fully validate the model. Thus far, our model is benchmarked against cluster data from proton- and neutron-irradiated ODS and F/M specimens irradiated to 3 dpa at 500°C. After both irradiations, Fe-9%Cr ODS exhibited partial dissolution of the Y-Ti-O nanoclusters resulting in a bimodal size distribution. Meanwhile, F/M alloys HCM12A and HT9 exhibit two types of irradiation-induced nanoclusters: Si-Mn-Ni-Cu clusters, and Cr-rich clusters to various degrees of coarsening. Although the model is capable of predicting each of these various results, additional data to establish the nucleation threshold and evolution rate of clusters will make the model more robust and applicable to other irradiation conditions (e.g. neutrons, self-ions) and alloys, making the model more versatile. This project will focus on the same Fe-9%Cr ODS, HCM12A and HT9 alloys, each irradiated with 2.0 MeV protons to 1 dpa and 7 dpa at 500°C. Characterization of samples irradiated to 1 dpa will elucidate the nucleation rate and evolution rate of new clusters, while characterization of 7 dpa specimens will confirm the long-term cluster stability of the bimodal size distribution of Y-Ti-O clusters in the ODS alloy. The project will enable validation of the Nelson, et al. approach as a viable model of cluster evolution in irradiated b.c.c. Fe-based alloys, providing a valuable technique to assist nanofeatured alloy development, which are of growing interest to the Department of Energy Office of Nuclear Energy, due to their enhanced radiation resistance. |
| Award Announced Date | 2016-08-16T13:01:10.163 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Matthew Swenson |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 710 |