NSUF 20-4159: Effects of helium on the defect accumulation under ion implantation in a Fe-9Cr alloy
Helium can be produced in the structure materials of nuclear reactors due to neutron irradiation induced transmutation. It strongly binds to vacancies produced by displacement cascades and hence preventing their recombination with interstitials. The interaction of helium-vacancy cluster with point defects formed in displacement cascade can significantly modify the biased sinks for point defects thus modifying the formation and combination of irradiation-induced defects as well as the associated strain field. In this experiment, we propose to perform careful in situ concurrent dual beam (heavy ion + He) irradiation experiments to clarify the role of helium in defect retention as a function of dose and temperature using the recently upgraded IVEM facility at ANL. Here we will use a potential candidate material for Generation IV fission reactors, bcc Fe-based alloys Fe-9Cr. In particular, we propose to investigate 3 temperatures, liquid He temperature, room temperature and 300 °C. The rationale behind choosing these three temperatures are that at liquid temperature the vacancies and interstitials are frozen; at room temperature only interstitials are mobile in Fe-9Cr; and at 300 °C both vacancies and interstitials are mobile. At each temperature, we propose to investigate two different implantation arrangements: Fe self-ion implantation, and dual-beam Fe self-ion and He implantation. Afterward, we will use state-of-art HR-TKD to map the strain field associated with the defects in the above mentioned samples. Comparison among the strain fields will allow us to directly visualize the effect of co-injected helium on defect structure evolution and defect-defect interaction as function of temperature and dose. Overall this leads to 6 distinct experiments, request 5 days of experimental time. The results of these experiments, will enable us to perform a systematic and detailed study of defect interactions with and without helium as a function of dose and temperature. This is essential for direct comparison with computational models that seek to capture the effect of injected gas on defect retention. Our observations will be used to benchmark simulations ranging from the electronic structure to macroscopic scale developed by our collaborators at the UKAEA.
Additional Info
| Field | Value |
|---|---|
| Abstract | Helium can be produced in the structure materials of nuclear reactors due to neutron irradiation induced transmutation. It strongly binds to vacancies produced by displacement cascades and hence preventing their recombination with interstitials. The interaction of helium-vacancy cluster with point defects formed in displacement cascade can significantly modify the biased sinks for point defects thus modifying the formation and combination of irradiation-induced defects as well as the associated strain field. In this experiment, we propose to perform careful in situ concurrent dual beam (heavy ion + He) irradiation experiments to clarify the role of helium in defect retention as a function of dose and temperature using the recently upgraded IVEM facility at ANL. Here we will use a potential candidate material for Generation IV fission reactors, bcc Fe-based alloys Fe-9Cr. In particular, we propose to investigate 3 temperatures, liquid He temperature, room temperature and 300 °C. The rationale behind choosing these three temperatures are that at liquid temperature the vacancies and interstitials are frozen; at room temperature only interstitials are mobile in Fe-9Cr; and at 300 °C both vacancies and interstitials are mobile. At each temperature, we propose to investigate two different implantation arrangements: Fe self-ion implantation, and dual-beam Fe self-ion and He implantation. Afterward, we will use state-of-art HR-TKD to map the strain field associated with the defects in the above mentioned samples. Comparison among the strain fields will allow us to directly visualize the effect of co-injected helium on defect structure evolution and defect-defect interaction as function of temperature and dose. Overall this leads to 6 distinct experiments, request 5 days of experimental time. The results of these experiments, will enable us to perform a systematic and detailed study of defect interactions with and without helium as a function of dose and temperature. This is essential for direct comparison with computational models that seek to capture the effect of injected gas on defect retention. Our observations will be used to benchmark simulations ranging from the electronic structure to macroscopic scale developed by our collaborators at the UKAEA. |
| Award Announced Date | 2020-07-14T14:10:35.3 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Wei-Ying Chen |
| Irradiation Facility | None |
| PI | Hongbing Yu |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4159 |