NSUF 15-590: Nanoscale solute clusters and a' precipitates in irradiated Fe-Cr alloys neutron irradiated at 290C
High chromium ferritic/martensitic (F-M) steels are one of the strong contenders for structural components of the next generation of nuclear reactors and future fusion reactors. The long-term use of these steels in intense neutron irradiation environments requires reliable predictions of the evolution of their microstructures and mechanical properties. Developing accurate models that can predict phase transformations, accelerated diffusion, and other irradiation-affected phenomena, requires experimental insight and validation. The structural changes induced by irradiation in Fe-Cr steels, which have been extensively reported, are complex and include Ni and Si clustering, solute segregation to dislocations, grain boundary Cr segregation or Cr depletion. Prior work on multicomponent steels, such as austenitic stainless steels and low alloy ferritic pressure vessel steels, has also revealed a sensitivity of the radiation response to small variations, not only in alloy solute contents, but also trace impurity concentrations. A number of outstanding questions remain concerning the microstructural features, specifically the mechanisms by which they form: radiation induced segregation or radiation enhanced diffusion. The PI and collaborators on a series of neutron irradiated Fe-Cr alloys have already demonstrated the impact of using atom probe tomography to determine the phase boundary for the a/a’ decomposition [Bachhav et al. Scripta Materialia 2013], to quantitatively measure dislocation loop distribution and habit planes, and to quantify solute segregation to dislocations, grain boundaries or second phase particles [Bachhav et al. J. Nucl. Mater. 2014]. Therefore using the same experimental approach in combination with transmission electron microscopy and microhardness measurements, the proposed work focuses on expanding the characterization of the alloys to high doses to probe saturation, confirm the stability of the microstructure already observed at a lower dose, and link with mechanical response. The expected period of performance is Sept 2015-March 2016 depending on sample and instrument availability. The proposed work directly addresses the programmatic need for developing and benchmarking predictive models for material degradation through quantitative microstructure evolution and microstructure/ hardening relationships. It also addresses the need to validate the use of ion implantation by comparing these data with other on-going experimental work by the PI on similar Fe-Cr alloys.
Additional Info
| Field | Value |
|---|---|
| Abstract | High chromium ferritic/martensitic (F-M) steels are one of the strong contenders for structural components of the next generation of nuclear reactors and future fusion reactors. The long-term use of these steels in intense neutron irradiation environments requires reliable predictions of the evolution of their microstructures and mechanical properties. Developing accurate models that can predict phase transformations, accelerated diffusion, and other irradiation-affected phenomena, requires experimental insight and validation. The structural changes induced by irradiation in Fe-Cr steels, which have been extensively reported, are complex and include Ni and Si clustering, solute segregation to dislocations, grain boundary Cr segregation or Cr depletion. Prior work on multicomponent steels, such as austenitic stainless steels and low alloy ferritic pressure vessel steels, has also revealed a sensitivity of the radiation response to small variations, not only in alloy solute contents, but also trace impurity concentrations. A number of outstanding questions remain concerning the microstructural features, specifically the mechanisms by which they form: radiation induced segregation or radiation enhanced diffusion. The PI and collaborators on a series of neutron irradiated Fe-Cr alloys have already demonstrated the impact of using atom probe tomography to determine the phase boundary for the a/a’ decomposition [Bachhav et al. Scripta Materialia 2013], to quantitatively measure dislocation loop distribution and habit planes, and to quantify solute segregation to dislocations, grain boundaries or second phase particles [Bachhav et al. J. Nucl. Mater. 2014]. Therefore using the same experimental approach in combination with transmission electron microscopy and microhardness measurements, the proposed work focuses on expanding the characterization of the alloys to high doses to probe saturation, confirm the stability of the microstructure already observed at a lower dose, and link with mechanical response. The expected period of performance is Sept 2015-March 2016 depending on sample and instrument availability. The proposed work directly addresses the programmatic need for developing and benchmarking predictive models for material degradation through quantitative microstructure evolution and microstructure/ hardening relationships. It also addresses the need to validate the use of ion implantation by comparing these data with other on-going experimental work by the PI on similar Fe-Cr alloys. |
| Award Announced Date | 2015-08-10T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Emmanuelle Marquis |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 590 |