Abnormal grain growth in iron-containing SiC fibers |
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Authors: | Yanwen Li Hongbo Nie Sikang Xue Chongze Hu Congying Xiang Xiaohui Su Jian Luo Siwei Li Zhiyang Yu |
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Affiliation: | 1. Fujian Key Laboratory of Advanced Materials, Key Laboratory of High Performance Ceramic Fibers (Ministry of Education), College of Materials, Xiamen University, Xiamen, 361005, People’s Republic of China;2. State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, People’s Republic of China;3. School of Materials Science & Engineering, Baise University, Baise, 533000, People’s Republic of China;4. Department of NanoEngineering, Program of Materials Science and Engineering, University of California, San Diego, La Jolla, CA, 92093-0448, USA |
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Abstract: | Understanding the role of sintering aids during microstructure evolution is critical to the manufacture of densified SiC fibers. A variety of TEM characterization techniques are combined to investigate grain growth behavior in iron-doped SiC fibers. Ultra-large SiC grains in micron size, as the self-assembly of nano sub-grains into a similar orientation, were consistently discovered at the surface and indicative of abnormal grain growth. The growth front consisted of polycrystalline nanograins wetted by iron-rich particles, where several sub-grains were found to unify their (111) planes with a misorientation angle less than 10°, indicating grain rotation at the growth front. It is proposed that iron-rich particles form a quasi-liquid interfacial phase during sintering, which facilitates coherent attachment of grains and results in fast grain growth using neighboring irregular-shaped nanograins as building blocks. The imperfect ordered coalescence of nanograins introduces structural heterogeneities, including low angle grain boundaries and porosities. |
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Keywords: | Abnormal grain growth Iron-containing SiC fibers Transmission electron microscopy Coherent attachment |
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