Microstructure and Mechanical Properties of Hot-Pressed Silicon Carbide-Aluminum Nitride Compositions |
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Authors: | Youren Xu Avigdor Zangvil Martine Landon François Thevenot |
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Affiliation: | Materials Research Laboratory and Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801;Department Materiaux, Ecole Nationale Superieure des Mines de Saint-Etienne 42023 Saint-Etienne Cedex 2, France |
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Abstract: | A flexural strength of up to 1 GPa was achieved in SiC-AIN materials and is attributed to a dense, equiaxial grain structure of the 2H(δ) SiC-AIN solid solution, with a relatively uniform grain size of ~ 1 μm. The strength was found to decrease with increasing grain size. While the β→α phase transformation and the formation of various metastable polytypes make microstructural control difficult in SiC materials, excellent control is facilitated in SiC-AIN materials as a result of the stable 2H solid solution. Several mechanisms of grain refinement during the β→ 2H transition were observed, most notably the direct formation of several 2H grains from a single β grain. In addition, grain growth is limited by the diffusion-controlled nature of the transition. These mechanisms could be utilized to achieve even higher strength values, with potentially higher reliability of the materials in structural applications. |
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Keywords: | silicon carbide aluminum nitride microstructure mechanical properties solid solutions |
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