NSUF 16-683: A TEM study of proton, heavy-ion and neutron irradiated FeCr
in nuclear materials research, it is essential to be able to replicate the neutron damage that is expected within future reactors. Though irradiation by neutrons in materials testing reactors is the closest analogue to advanced reactor designs such as generation IV, charged particle irradiations are often preferred. Heavy ion irradiation is capable of producing high doses in relatively short periods of time, with little or no induced radioactivity and a great deal of control over the experimental variables. Proton irradiation is also useful as it has a homogenous and deep dose profile that is more suited to micromechanical testing, and lacks self-injected interstitial atoms in the region of interest. This work will study the microstructural damage by Transmission Electron Microscopy (TEM) of heavy ion and proton irradiated material, and compare these with neutron irradiated material under matching (as close as possible) irradiation conditions. This is an important study into the relevance of surrogate particle irradiations for studying neutron damage.A crucial and unavoidable difference between neutron, proton and heavy ion irradiation is the dose rate. FeCr alloys irradiated to matching dose with different dose rates have been shown to have significant differences in the post-irradiation microstructure and hardness. With neutron, proton and heavy ion irradiation, a wide range of dose rates from ~10-8 to ~10-5dpa/s can be studied. The 6 days FIB time requested at the CAES facility will be used to produce an array of TEM foils as far as being ready for lift out from the bulk material. This work will be conducted on two neutron irradiated FeCr binary alloys; Fe6Cr and Fe9Cr (shipped to CAES by UCSB). Since TEM foils are very delicate and highly vulnerable to surface oxidation and damge, it is very important the final lift out and thinning process is conducted immediately (ideally within 24 hours) before being studied in the TEM. For this reason, the foils will only be prepared at CAES as far as being ready for the lift out and thinning process. These final steps of the foil preparation will be conducted at the Culham Centre for Fusion Energy (CCFE) (funded outside of this proposal). Nano-indentation will also be conducted at CCFE. The accompanying work into heavy ion and proton irradiation will be performed in Oxford. Prior to any FIB work, the neutron irradiated materials will require polishing to obtain a flat and high quality finish (suitable for EBSD) which is essential for quality FIB work and near surface mechanical testing (nano-indentation). A typical polishing procedure for this type of work would be with grit papers up to 4000 grade, followed by polishing with diamond pastes of 3 and 1µm grade, and finally with colloidal silica. A similar process is advised here, to be conducted during the requested 1 day access to the preparation facilities at CAES. Due to the radioactive nature of the sample, extensive assistance will be required during this stage.
Additional Info
| Field | Value |
|---|---|
| Abstract | in nuclear materials research, it is essential to be able to replicate the neutron damage that is expected within future reactors. Though irradiation by neutrons in materials testing reactors is the closest analogue to advanced reactor designs such as generation IV, charged particle irradiations are often preferred. Heavy ion irradiation is capable of producing high doses in relatively short periods of time, with little or no induced radioactivity and a great deal of control over the experimental variables. Proton irradiation is also useful as it has a homogenous and deep dose profile that is more suited to micromechanical testing, and lacks self-injected interstitial atoms in the region of interest. This work will study the microstructural damage by Transmission Electron Microscopy (TEM) of heavy ion and proton irradiated material, and compare these with neutron irradiated material under matching (as close as possible) irradiation conditions. This is an important study into the relevance of surrogate particle irradiations for studying neutron damage.A crucial and unavoidable difference between neutron, proton and heavy ion irradiation is the dose rate. FeCr alloys irradiated to matching dose with different dose rates have been shown to have significant differences in the post-irradiation microstructure and hardness. With neutron, proton and heavy ion irradiation, a wide range of dose rates from ~10-8 to ~10-5dpa/s can be studied. The 6 days FIB time requested at the CAES facility will be used to produce an array of TEM foils as far as being ready for lift out from the bulk material. This work will be conducted on two neutron irradiated FeCr binary alloys; Fe6Cr and Fe9Cr (shipped to CAES by UCSB). Since TEM foils are very delicate and highly vulnerable to surface oxidation and damge, it is very important the final lift out and thinning process is conducted immediately (ideally within 24 hours) before being studied in the TEM. For this reason, the foils will only be prepared at CAES as far as being ready for the lift out and thinning process. These final steps of the foil preparation will be conducted at the Culham Centre for Fusion Energy (CCFE) (funded outside of this proposal). Nano-indentation will also be conducted at CCFE. The accompanying work into heavy ion and proton irradiation will be performed in Oxford. Prior to any FIB work, the neutron irradiated materials will require polishing to obtain a flat and high quality finish (suitable for EBSD) which is essential for quality FIB work and near surface mechanical testing (nano-indentation). A typical polishing procedure for this type of work would be with grit papers up to 4000 grade, followed by polishing with diamond pastes of 3 and 1µm grade, and finally with colloidal silica. A similar process is advised here, to be conducted during the requested 1 day access to the preparation facilities at CAES. Due to the radioactive nature of the sample, extensive assistance will be required during this stage. |
| Award Announced Date | 2016-08-16T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Steve Roberts |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 683 |