NSUF 25-5225: Mechanical Properties Characterization and Atom Probe Tomography Preparation of BOR60 Neutron Irradiated T91 Steel Samples for Surrogate Ion-Irradiation Comparison
T91 is a ferritic/martensitic (F/M) steel being investigated as a promising candidate material for structural components in a number of Generation IV nuclear reactor designs. It is a 9 wt% Cr steel, with a fine, complex microstructure, imparting high mechanical strength and good resistance to corrosion. The response of T91 steel under high temperature and high dose neutron irradiation must be fully characterized in order to inform its use in Gen IV reactor designs. Irradiation-induced microstructural changes detrimentally effect the mechanical performance of F/M steels. Thus, understanding the microstructural evolution, and correlating it with the mechanical response is a key step in technological development.
Without an active Gen IV prototype, surrogate methods must be utilized. Heavy ion irradiation as a surrogate to emulate neutron irradiation damage has many advantages and is the subject of multiple long-running DoE consortium of activities. Ion irradiation can achieve damage rates 10^4 times faster than reactor irradiation with negligible residual activity, reducing the cost of experiments and allowing post-irradiation characterization to be carried out without the need of hot facilities. However, to validate the efficacy of this technique in T91, the microstructure and mechanical properties of both self-ion irradiated and neutron irradiated materials must be characterized and compared.
The objective of the research that this RTE proposal would facilitate is to predict the observed irradiation-induced hardening with the microstructural changes using an advanced and novel dispersed barrier hardening model (DBHM), and compare this to measured nanoindentation data, for a full set of equivalently ion- and neutron-irradiated sample pairs of T91 steel. The irradiations span the dose and temperature range 15-35 dpa at 350-550 °C respectively, matching the expected operational temperature window for Fe-Cr F/M steels used in Gen IV reactors. The seven specimens requested for this RTE are held in the LAMDA laboratory storage at Oak Ridge National Laboratory, and the characterization and preparation methods proposed are available on LAMDA equipment.
Completing the microstructural and mechanical characterizations of the neutron-irradiated samples will complete a body of work spanning over a decade on these samples. This proposed RTE focuses on acquiring data up to now missing from the investigation, including Vickers hardness and nanoindentation measurements on seven neutron-irradiated samples and preparation of two atom probe tomography (APT) samples to complete this investigation. Polishing of the samples and optical imaging to enable pile-up correction to nanoindentation data is also proposed. We propose 88 hrs of NSUF-supported work in LAMDA with additional time for sample preparation, split into 56 hours for nanoindentation, 16 hours for Vickers hardness, and 16 hours for FIB APT tip preparation to be completed within 6 months of an award.
The outcome will allow full comparison of the BOR60 samples to the equivalent dual-ion samples to be made, and our analysis based on these characterizations will further the state-of-the-art by introducing methods which build on recently published DBHM research with novel improvements and consideration for high temperature microstructural behavior to predict experimental outcomes where DBH models broke down previously.
其他信息
| 域 | 价值 |
|---|---|
| Award Announced Date | 2025-08-06T10:06:28.207 |
| Awarded Institution | University of Oxford |
| Facility Tech Lead | Kory Linton |
| Irradiation Facility | |
| PI | Hannah Jones |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | None |