NSUF 20-4192: Phase stability of a’ precipitates in pre-aged Fe-25Cr model binary alloys after ion irradiation
High Cr (≥9%Cr) ferritic/martensitic (F/M) steels are important candidate structural materials for advanced reactors. However, the formation of dislocation loops and Cr-enrich alpha prime (α’) precipitates during irradiation will lead to severe problem with the application of this alloy, that is radiation induced hardening and increase of ductile to brittle transition temperature. α’ precipitates have BCC structure and they are fully coherent with Fe-enriched matrix. The objective of this proposal is to investigate the ion irradiation response of different sink strength (S=2πNd, where N is precipitate number density and d is precipitate diameter) α’ precipitates contained Fe-25Cr model alloys. APT lift-outs from six pre-aged (500 oC for 0, 600 and 900 h) Fe-25Cr model binary alloys with and without ion irradiations will be investigated by using LEAP 4000X HR atom probe tomography in MaCS facility. Three of them were in-situ irradiated with 1 MeV Kr++ ions at 350 oC up to 1.5 dpa when the dose rate was controlled at 10-4 dpa/s, using the IVEM facilities located in Argonne National Laboratory, the remaining three lift-outs were the references only heat treated to form Cr-enriched alpha prime precipitates. The samples’ irradiation or aging conditions were listed in RTE Narrative file. Here we requested a total access of 15 days to CAES-MaCS including 3 days for needle preparation using the SEM-FIB in MaCS facility and 12 days for data collection using LEAP 4000X HR atom probe tomography. For the reference samples, the APT needles should be retracted from the polished side, the location is not important. For the irradiated samples, the beam size of the ion irradiaation was 1.5 mm in diameter, the APT needles will be retracted from locations about 0.5 mm away from jet-polish-produced hole, where the thickness of the area was less than 500 nm, to make sure the lift-outs were within the whole range of irradiation damage region, based on SRIM calculation, where damage depth was predicted as 500 nm. The proposing team has extensive experience with using FIB to prepare APT samples and data collection and analysis, so the lift-out of APT needles will be conducted in the home institute and the sharpening will be finished using the FIB in MaCS facility. The recommended running conditions for data acquisition is using electric mode at 50 K, with pulse frequency of 200 kHz, pulse fraction of 20% and detection rate of 0.5 %. The reconstruction and further data analysis will be performed at Oak Ridge National Laboratory, no additional time is requested. By the completion of data analysis, the radius, number density, Cr concentration in precipitates or matrix and volume fraction of precipitates will be obtained. This project will provide valuable references for the development of nuclear structural materials and contribute to the DOE Nuclear Energy Roadmap in the search for materials that can meet the challenges in materials R&D for advanced reactor systems that contribute to the Administration’s energy security and climate change goals.
Additional Info
| Field | Value |
|---|---|
| Abstract | High Cr (≥9%Cr) ferritic/martensitic (F/M) steels are important candidate structural materials for advanced reactors. However, the formation of dislocation loops and Cr-enrich alpha prime (α’) precipitates during irradiation will lead to severe problem with the application of this alloy, that is radiation induced hardening and increase of ductile to brittle transition temperature. α’ precipitates have BCC structure and they are fully coherent with Fe-enriched matrix. The objective of this proposal is to investigate the ion irradiation response of different sink strength (S=2πNd, where N is precipitate number density and d is precipitate diameter) α’ precipitates contained Fe-25Cr model alloys. APT lift-outs from six pre-aged (500 oC for 0, 600 and 900 h) Fe-25Cr model binary alloys with and without ion irradiations will be investigated by using LEAP 4000X HR atom probe tomography in MaCS facility. Three of them were in-situ irradiated with 1 MeV Kr++ ions at 350 oC up to 1.5 dpa when the dose rate was controlled at 10-4 dpa/s, using the IVEM facilities located in Argonne National Laboratory, the remaining three lift-outs were the references only heat treated to form Cr-enriched alpha prime precipitates. The samples’ irradiation or aging conditions were listed in RTE Narrative file. Here we requested a total access of 15 days to CAES-MaCS including 3 days for needle preparation using the SEM-FIB in MaCS facility and 12 days for data collection using LEAP 4000X HR atom probe tomography. For the reference samples, the APT needles should be retracted from the polished side, the location is not important. For the irradiated samples, the beam size of the ion irradiaation was 1.5 mm in diameter, the APT needles will be retracted from locations about 0.5 mm away from jet-polish-produced hole, where the thickness of the area was less than 500 nm, to make sure the lift-outs were within the whole range of irradiation damage region, based on SRIM calculation, where damage depth was predicted as 500 nm. The proposing team has extensive experience with using FIB to prepare APT samples and data collection and analysis, so the lift-out of APT needles will be conducted in the home institute and the sharpening will be finished using the FIB in MaCS facility. The recommended running conditions for data acquisition is using electric mode at 50 K, with pulse frequency of 200 kHz, pulse fraction of 20% and detection rate of 0.5 %. The reconstruction and further data analysis will be performed at Oak Ridge National Laboratory, no additional time is requested. By the completion of data analysis, the radius, number density, Cr concentration in precipitates or matrix and volume fraction of precipitates will be obtained. This project will provide valuable references for the development of nuclear structural materials and contribute to the DOE Nuclear Energy Roadmap in the search for materials that can meet the challenges in materials R&D for advanced reactor systems that contribute to the Administration’s energy security and climate change goals. |
| Award Announced Date | 2020-07-14T14:14:14.993 |
| Awarded Institution | Idaho National Laboratory |
| Facility | Advanced Test Reactor |
| Facility Tech Lead | Alina Zackrone, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Ling Wang |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4192 |