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Microstructure of Neutron-Irradiated Al3Hf-Al Thermal Neutron Absorber Materials
Donna Post Guillen1, Janelle Wharry2, Yu Lu3
1Idaho National Laboratory, 995 University Blvd., Idaho Falls, ID 83401, USA.
Materials (Basel, Switzerland)
|February 26, 2025
Summary
This study developed an aluminum-hafnium composite (Al3Hf-Al MMC) for neutron absorption in nuclear reactors. Irradiated samples showed microstructural changes, indicating potential for advanced spectral tailoring.
Area of Science:
- Materials Science
- Nuclear Engineering
- Metallurgy
Background:
- Development of advanced materials for nuclear reactors is crucial for optimizing performance and safety.
- Metal matrix composites (MMCs) offer unique properties for demanding environments.
- Neutron absorbers are essential for controlling reactor spectra and enabling specific material testing.
Purpose of the Study:
- To develop and characterize a novel thermal neutron-absorbing MMC composed of aluminum hafnium (Al3Hf) particles in an aluminum matrix.
- To investigate the microstructural stability of this Al3Hf-Al MMC under neutron irradiation conditions.
- To assess the potential of this MMC for spectral tailoring in mixed-spectrum nuclear reactors.
Main Methods:
- Fabrication of Al3Hf-Al MMCs using powder metallurgy and hot pressing.
- Neutron irradiation of specimens to doses between 1.12 and 5.38 dpa at temperatures of 286-400 °C.
- Microstructural analysis using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS).
- Application of a YOLOv11 computer vision model for identifying dislocation structures in TEM images.
Main Results:
- All examined samples, including irradiated and control specimens, exhibited oxide presence at the Al3Hf particle-aluminum matrix interface.
- Irradiated specimens displayed the formation of needle-like structures emanating from the Al3Hf particles into the aluminum matrix.
- TEM analysis revealed microstructural evolution, including dislocation lines and loops, within the irradiated MMCs.
Conclusions:
- The Al3Hf-Al MMCs demonstrate microstructural stability under relevant irradiation conditions.
- The observed microstructural changes provide insights into the material's behavior in a fast flux environment.
- This Al3Hf-Al MMC shows promise as a novel neutron absorber for advanced spectral tailoring in nuclear reactors.
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