NSUF 18-1400: Characterization and modeling of secondary phase evolution in an irradiated Zr-1.0Nb alloy
The objective of this project is to characterize the solute nanocluster morphology and evolution in a Zr-1.0Nb alloy prior to and following irradiation with Kr2+ ions to 10 dpa at 310°C. The results of this study will enable direct comparison with previously characterized specimens from the same alloy irradiated with fast neutrons to the same dose (10 dpa) and temperature (310°C). Zirconium based alloys are commonly used as cladding materials in both light water reactors (LWRs) and heavy water reactor applications. Therefore, it is critical to have a clear understanding of how the microstructures of these alloys will evolve with long-term irradiation. Charged particle irradiations, including heavy ions, are widely used to emulate neutron irradiation effects in candidate materials. Ions deliver high damage rates in short experimental time frames, at lower costs, and with little to no residual radioactivity. However, the dose rate and damage cascade morphologies differ widely between ions and neutrons. Currently, there is limited understanding of the significance of these physical differences and how they manifest in the resultant microstructure and mechanical properties of target alloys. A calculation model has been advanced to predict the change in nanocluster radius over irradiation time (i.e. dose) using the theory of Nelson, Hudson, and Mazey (NHM). This method has previously been successful at modeling nanocluster size evolution in three separate Fe-based alloys, while offering a means to estimate the temperature shift required for ion irradiation to emulate neutron irradiation-induced nanocluster evolution. We hypothesize this model is transferrable to other systems, including h.c.p. Zr-based alloys like the one in question. Atom probe tomography (APT) is the ideal technique to measure the values required to parameterize the model. As a result, the primary thrust of this experiment is to characterize the secondary nanoscale phases and the respective solute distributions in the as-received and Kr2+ irradiated specimens to parameterize a NHM-based model for the Zr-1.0Nb alloy system.
This project focuses on three Zr-1.0Nb alloy specimens, available at the following conditions: a) as-received, b) 1 MeV Kr2+ ion-irradiated to 10 dpa at 310°C, and c) fast neutron-irradiated to 10 dpa at 310°C (previously characterized). Characterization of the as-received specimen will confirm the presence (or absence) of any pre-existing nanoscale phases and establish the baseline distribution of solutes for parameterizing the NHM model. With characterization of the Kr2+ irradiated specimen, we can draw a direct comparison with the previously analyzed neutron-irradiated specimen to common irradiation dose and temperature. The data from each will enable set up of the model and determination of the estimated temperature shift required for Kr2+ irradiation to emulate the nanocluster evolution observed upon neutron irradiation. The project will enable simulation of solute cluster size evolution and estimation of the temperature shift required for Kr2+ irradiation to successfully emulate neutron irradiation in a Zr-1.0N alloy. The project will inform future work to prescribe a follow up Kr2+ irradiation experiment at the predicted temperature shift to test the efficacy of the model and the temperature shift requirement.
Additional Info
| Field | Value |
|---|---|
| Abstract | The objective of this project is to characterize the solute nanocluster morphology and evolution in a Zr-1.0Nb alloy prior to and following irradiation with Kr2+ ions to 10 dpa at 310°C. The results of this study will enable direct comparison with previously characterized specimens from the same alloy irradiated with fast neutrons to the same dose (10 dpa) and temperature (310°C). Zirconium based alloys are commonly used as cladding materials in both light water reactors (LWRs) and heavy water reactor applications. Therefore, it is critical to have a clear understanding of how the microstructures of these alloys will evolve with long-term irradiation. Charged particle irradiations, including heavy ions, are widely used to emulate neutron irradiation effects in candidate materials. Ions deliver high damage rates in short experimental time frames, at lower costs, and with little to no residual radioactivity. However, the dose rate and damage cascade morphologies differ widely between ions and neutrons. Currently, there is limited understanding of the significance of these physical differences and how they manifest in the resultant microstructure and mechanical properties of target alloys. A calculation model has been advanced to predict the change in nanocluster radius over irradiation time (i.e. dose) using the theory of Nelson, Hudson, and Mazey (NHM). This method has previously been successful at modeling nanocluster size evolution in three separate Fe-based alloys, while offering a means to estimate the temperature shift required for ion irradiation to emulate neutron irradiation-induced nanocluster evolution. We hypothesize this model is transferrable to other systems, including h.c.p. Zr-based alloys like the one in question. Atom probe tomography (APT) is the ideal technique to measure the values required to parameterize the model. As a result, the primary thrust of this experiment is to characterize the secondary nanoscale phases and the respective solute distributions in the as-received and Kr2+ irradiated specimens to parameterize a NHM-based model for the Zr-1.0Nb alloy system. This project focuses on three Zr-1.0Nb alloy specimens, available at the following conditions: a) as-received, b) 1 MeV Kr2+ ion-irradiated to 10 dpa at 310°C, and c) fast neutron-irradiated to 10 dpa at 310°C (previously characterized). Characterization of the as-received specimen will confirm the presence (or absence) of any pre-existing nanoscale phases and establish the baseline distribution of solutes for parameterizing the NHM model. With characterization of the Kr2+ irradiated specimen, we can draw a direct comparison with the previously analyzed neutron-irradiated specimen to common irradiation dose and temperature. The data from each will enable set up of the model and determination of the estimated temperature shift required for Kr2+ irradiation to emulate the nanocluster evolution observed upon neutron irradiation. The project will enable simulation of solute cluster size evolution and estimation of the temperature shift required for Kr2+ irradiation to successfully emulate neutron irradiation in a Zr-1.0N alloy. The project will inform future work to prescribe a follow up Kr2+ irradiation experiment at the predicted temperature shift to test the efficacy of the model and the temperature shift requirement. |
| Award Announced Date | 2018-05-17T10:59:00.893 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Matthew Swenson |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1400 |