NSUF 15-569: Characterizing Si-Ni-Mn clustering in ion irradiated Fe-9Cr ODS alloy
The objective of this project is to understand the role of Si, Ni, and Mn clustering in irradiated ODS alloys. Oxide-dispersion strengthened (ODS) alloys are nanofeatured materials, having grains of diameter ~250 nm, and containing a dispersion of oxide nanoparticles. The fine grains and oxide nanoparticles provide the alloy with high strength at elevated temperatures and dimensional stability under irradiation, making ODS alloys leading candidates for structural components in fusion and advanced fission reactors. Most post-irradiation evaluation (PIE) experiments of ODS alloys have focused on evaluating the radiation stability of the oxide nanoparticles. There have been no studies, to our knowledge, of Si, Ni, and Mn clustering in ODS alloys. But through previous ATR-NSUF rapid turnaround experiments, we have observed clustering of Si, Ni, and Mn in a model Fe-9Cr ODS steel irradiated with neutrons (3 dpa, 500°C), protons (3 dpa, 500°C), and Fe++ ions (100 dpa, 400°C). Results have shown the Si-Ni-Mn-rich clusters to form about existing oxide nanoparticles, which themselves dissolve under irradiation. This project will perform a more systematic irradiation series in order to more precisely evaluate the dose evolution of the Si-Ni-Mn-rich clusters and to ascertain a clearer understanding of the mechanisms of oxide dissolution and Si-Ni-Mn clustering. Furthermore, this project will provide insight into whether Si, Ni, and Mn clustering could stabilize the oxide nanoparticles under irradiation. The proposed project will focus on characterizing the irradiated microstructure and clustering behavior in a model Fe-9Cr ODS alloy irradiated to the following conditions through a previous ATR-NSUF rapid turnaround project: (1) 2.0 MeV protons, 1 dpa, 500°C (2) 5.0 MeV Fe++ ions, 1 dpa, 500°C (3) 5.0 MeV Fe++ ions, 3 dpa, 500°C Together with previously-studied samples, these irradiations will provide a proton and a Fe++ ion irradiation dose series at 500°C. Irradiation (3) also provides the identical dose and temperature as the previously-studied 500°C, 3 dpa proton and neutron irradiations. Having the same alloy irradiated with three different particles, but to otherwise identical conditions, is a rare and unique opportunity offered by this project, and it can potentially provide tremendous insight into the mechanistic differences between irradiation damage caused by neutrons versus protons versus self-ions. This project will help us understand the role of Si-Ni-Mn clustering in the irradiation stability of oxide nanoparticles in ODS steels, which is critical to the long-term material integrity of ODS alloys in cladding and structural components in fission and fusion reactors. Results of this project will be relevant to all ODS and other nanostructured alloys based on the b.c.c Fe-Cr matrix, 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 understand the role of Si, Ni, and Mn clustering in irradiated ODS alloys. Oxide-dispersion strengthened (ODS) alloys are nanofeatured materials, having grains of diameter ~250 nm, and containing a dispersion of oxide nanoparticles. The fine grains and oxide nanoparticles provide the alloy with high strength at elevated temperatures and dimensional stability under irradiation, making ODS alloys leading candidates for structural components in fusion and advanced fission reactors. Most post-irradiation evaluation (PIE) experiments of ODS alloys have focused on evaluating the radiation stability of the oxide nanoparticles. There have been no studies, to our knowledge, of Si, Ni, and Mn clustering in ODS alloys. But through previous ATR-NSUF rapid turnaround experiments, we have observed clustering of Si, Ni, and Mn in a model Fe-9Cr ODS steel irradiated with neutrons (3 dpa, 500°C), protons (3 dpa, 500°C), and Fe++ ions (100 dpa, 400°C). Results have shown the Si-Ni-Mn-rich clusters to form about existing oxide nanoparticles, which themselves dissolve under irradiation. This project will perform a more systematic irradiation series in order to more precisely evaluate the dose evolution of the Si-Ni-Mn-rich clusters and to ascertain a clearer understanding of the mechanisms of oxide dissolution and Si-Ni-Mn clustering. Furthermore, this project will provide insight into whether Si, Ni, and Mn clustering could stabilize the oxide nanoparticles under irradiation. The proposed project will focus on characterizing the irradiated microstructure and clustering behavior in a model Fe-9Cr ODS alloy irradiated to the following conditions through a previous ATR-NSUF rapid turnaround project: (1) 2.0 MeV protons, 1 dpa, 500°C (2) 5.0 MeV Fe++ ions, 1 dpa, 500°C (3) 5.0 MeV Fe++ ions, 3 dpa, 500°C Together with previously-studied samples, these irradiations will provide a proton and a Fe++ ion irradiation dose series at 500°C. Irradiation (3) also provides the identical dose and temperature as the previously-studied 500°C, 3 dpa proton and neutron irradiations. Having the same alloy irradiated with three different particles, but to otherwise identical conditions, is a rare and unique opportunity offered by this project, and it can potentially provide tremendous insight into the mechanistic differences between irradiation damage caused by neutrons versus protons versus self-ions. This project will help us understand the role of Si-Ni-Mn clustering in the irradiation stability of oxide nanoparticles in ODS steels, which is critical to the long-term material integrity of ODS alloys in cladding and structural components in fission and fusion reactors. Results of this project will be relevant to all ODS and other nanostructured alloys based on the b.c.c Fe-Cr matrix, which are of growing interest to the Department of Energy Office of Nuclear Energy, due to their enhanced radiation resistance. |
| Award Announced Date | 2015-04-22T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Janelle Wharry |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 569 |