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Microstructure and Fracture Toughness of Al2O3/Er3Al5O12 Eutectic Ceramic Prepared by Laser Zone Remelting

Author(s): DENG Yang-Fang, ZHANG Jun, SU Hai-Jun, SONG Kan, LIU Lin, FU Heng-Zhi

Journal: Journal of Inorganic Materials
ISSN 1000-324X

Volume: 26;
Issue: 8;
Start page: 841;
Date: 2011;
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Keywords: oxide eutectic ceramic; laser zone remelting; microstructure; fracture toughness

Directionally solidified Al2O3/Er3Al5O12(EAG) eutectic ceramic was prepared by laser zone remelting technique. The eutectic morphology and microstructure evolution investigated as a function of laser scanning rate. Moreover, the mechanical properties and toughening mechanisms were studied. The Al2O3/EAG eutectic ceramic consists of only two continuous phases of Al2O3 and EAG which interpenetrates with each other to form well―distributed three―dimensional network. The eutectic spacing is only around 0.2―2.1μm and reduces with the increase of scanning rate. At low scanning rate, the typical lamellar irregular eutectic structure is obtained. When the scanning rate reaches 800μm/s, the cellular or dendrite microstructure appears. The hardness and the fracture toughness at room temperature are measured to be 18.7GPa and 2.45MPa·m1/2, respectively. The refined microstructure, crack deflection at phase interface and crack branching contribute to the improved toughness.
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