NSUF 24-4829: High Resolution Studies of Uranium Mononitride/Zirconium Carbide Composites for Advanced Fuels Applications

This project is an investigation of ultra-high temperature intergranular phases that precipitate in uranium mononitride/zirconium carbide, ceramic-ceramic composites at high temperature (~2000℃). UN/ZrC composites are being explored for high-temperature nuclear thermal propulsion reactors for missions to Mars and beyond. The fuel elements used in these reactors are subjected to flowing hot hydrogen and temperatures up to 2900℃ which has peculiar effects on the phase stability of the composite. Due to the intense environment, new and unidentified phases are precipitating along the grain boundaries as the composite homogenizes into a UZrCN quaternary phase. The samples (3) of various UN particle sizes exhibiting these behaviors have been evaluated using bulk x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) which suggest that the intergranular phases are a U(CNO) phase; however, these techniques do not have the nanoscopic resolution to quantitatively identify the phase and composition. Under this proposal, these intergranular phases will be evaluated using atom probe tomography (APT) and scanning transmission electron microscopy (STEM) to examine the unknown phase on a nanoscopic scale. To obtain these results, a focused-ion beam (FIB) is required to prepare the APT and STEM samples. These techniques will be able to quantitatively define what the phase precipitates around the grains are and whether they present any risk to the sample integrity through embrittlement. This behavior can then be directly correlated to the initial UN particles sizes used to create the samples. This phenomenon is important to understand due to the higher temperature demands being required in the aerospace and nuclear industry.

추가 정보

필드	값
Award Announced Date	2024-02-02T12:14:26.857
Awarded Institution	Idaho National Laboratory
Facility Tech Lead	Alina Montrose, Yaqiao Wu
Irradiation Facility
PI	Sarah Hamilton
PI Email	[email protected]
Project Type	RTE
RTE Number	None