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DOE OSTI · 2583967

Investigating Grain Structure and Microcracking in SiCf-SiCm Composites Using 4D-STEM

Yang, Guang [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]·Nguyen, Bao-Phong [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]·Rittenhouse, Joshua E. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]·Xu, Fei [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]·Gonderman, Sean [General Atomics, San Diego, CA (United States)]·Gazza, Jack [General Atomics, San Diego, CA (United States)]·Xu, Peng [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]·Yao, Tiankai [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]
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Abstract

Silicon carbide (SiC) fiber-reinforced SiC matrix composites (SiCf-SiCm) are promising materials for accident-tolerant fuel (ATF) cladding in light water reactors. This paper, using four-dimensional scanning transmission electron microscopy (4D-STEM), studied the microstructure of SiCf-SiCm at nanoscale and provided grain statistics at the CVI/fiber region. Here, the results reveal that CVI region mainly contain irregular sub-micron grains (115 nm to 1800 nm) with a preferred orientation, while the fiber region has nano equiaxed grains (21 nm to 78 nm) with random orientations. Centered dark field imaging over the fiber regions verified the grain size measurement by 4D-STEM. Through 4D-STEM virtual dark field imaging and orientation mapping, intragranular propagation was identified as the fracture mechanism for a microcrack observed within the CVI region. The amorphous pyrolytic carbon layer was also shown to effectively arrest the microcrack.

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4D-STEMCrack PropagationGrain BoundariesGrain OrientationSilicon carbide (SiC)

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Yang, Guang [Idaho National Laboratory (INL), Idaho Falls, ID (United States)], Nguyen, Bao-Phong [Idaho National Laboratory (INL), Idaho Falls, ID (United States)], Rittenhouse, Joshua E. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)], Xu, Fei [Idaho National Laboratory (INL), Idaho Falls, ID (United States)], Gonderman, Sean [General Atomics, San Diego, CA (United States)], Gazza, Jack [General Atomics, San Diego, CA (United States)], Xu, Peng [Idaho National Laboratory (INL), Idaho Falls, ID (United States)], Yao, Tiankai [Idaho National Laboratory (INL), Idaho Falls, ID (United States)]. 2025-05-28. Investigating Grain Structure and Microcracking in SiCf-SiCm Composites Using 4D-STEM. https://doi.org/10.1016/j.matchar.2025.115165

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