NSUF 24-4815: Dislocation-precipitate interaction under irradiation – in situ TEM nanomechanical testing during heavy ion irradiation
The Fukushima incident highlighted the urgent need for advanced cladding materials and fuels in light water reactors capable of withstanding extreme conditions. A primary goal in this context is to design an improved fuel system with exceptional resistance to oxidation in steam environments, particularly during a loss-of-coolant accident (LOCA). Among potential candidates, ferritic alloys with a high chromium (Cr) concentration (>9%) have seen extensive use in high-temperature applications and are now being considered as advanced cladding materials for light water reactors due to their ability to form a stable aluminum oxide scale at elevated temperatures. Commercially available FeCrAl alloys, including FeCralloy, PM2000, and Kanthal variants like AMPT, exhibit superior high-temperature mechanical properties characterized by enhanced strength and creep resistance.
One of the major objectives of the DOE-NE Advanced Fuel Campaign (AFC) is to advance our understanding of radiation-induced creep in advanced FeCrAl alloys, as radiation-induced creep significantly impacts the lifetime of these claddings. However, to advance physics-based radiation-induced creep modeling within the AFC, it is imperative to establish fundamental knowledge regarding how radiation influences the dislocation-precipitate interaction in FeCrAl alloys. Consequently, the proposal's objective is to enhance our comprehension of radiation-induced creep in advanced cladding alloys containing precipitates. This is to be achieved by performing in-situ transmission electron microscopy (TEM) irradiation-nanomechanical deformation experiments on precipitate-hardened FeCrAl alloys, thereby elucidating the fundamental physical mechanisms underlying dislocation-precipitate interaction during irradiation.
The Intermediate Voltage Electron Microscopy (IVEM) facility at Argonne National Laboratory is equipped with a room-temperature Picoindenter (PI) 95 and a high-temperature Gatan straining holder, enabling the conduct of in-situ TEM nanomechanical testing during heavy-ion irradiation. The irradiation is expected to impact dislocation-precipitate interaction through two proposed scenarios: (A) cascade-induced dislocation bypass and (B) radiation-induced dislocation climb. In Scenario A, cascades are generated at the dislocation-precipitate pinning points, leading to alterations in the local dislocation configuration and cascade-induced dislocation bypass. In Scenario B, cascades form away from the precipitates, and subsequent point defects migrate to the precipitates, resulting in radiation-induced dislocation climb. The fundamental relationship between dose rate, precipitate size, precipitate strain field, and cascade size on dislocation-precipitate bypass remains an elusive area of knowledge. Thus, we proposed to perform in-situ transmission electron microscopy (TEM) irradiation-nanomechanical deformation of precipitate-hardened FeCrAl alloys to elucidate the fundamental physical mechanisms of dislocation-precipitate interaction while under irradiation.
Successful completion of this research will significantly advance the state-of-the-art in materials science and the understanding of radiation effects on materials. It will offer critical insights into the relationship between precipitate characteristics, irradiation parameters, and dislocation-precipitate interactions. The knowledge derived from this study will establish a benchmark for the development of discrete dislocation dynamics models, enhancing the accuracy of simulations related to irradiated material creep and contributing the advancement of lifetime prediction capabilities for advanced FeCrAl alloys.
The anticipated scientific outcome of this experiment is expected to yield a deeper understanding of radiation-induced creep in advanced cladding alloys, potentially resulting in two high-impact publications (one paper on the in situ experiments and the other on the new model development). Specifically, the research will elucidate the intricate interactions between dislocations and precipitates under irradiation, advancing the field of materials science and offering valuable insights for the development of materials capable of withstanding extreme conditions in nuclear reactor environments, ultimately enhancing safety and performance within the nuclear industry.
Additional Info
| Field | Value |
|---|---|
| Award Announced Date | 2024-02-02T12:11:17.65 |
| Awarded Institution | Los Alamos National Laboratory |
| Facility Tech Lead | Wei-Ying Chen |
| Irradiation Facility | Intermediate Voltage Electron Microscopy (IVEM)-Tandem Facility |
| PI | Hi Vo |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | None |