Superplastic Behavior of Fine-Grained β-Silicon Nitride Material under Compression |
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Authors: | Guo-Dong Zhan Mamoru Mitomo Toshiyuki Nishimura Rong-Jun Xie Taketo Sakuma Yuichi Ikuhara |
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Affiliation: | National Institute for Research in Inorganic Materials, Tsukuba-shi, Ibaraki 305-0044, Japan;Department of Materials Science, University of Tokyo, Tokyo, Japan |
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Abstract: | The deformation behavior of a hot-pressed, fine-grained β-Si3N4 ceramic was investigated in the temperature range 1450°—1650°C, under compression, and the results for strain rate and temperature dependence of the flow stress are presented here. The present results show that the material is capable of high rates of deformation (∼10−4—10−3 s−1) within a wide range of deformation temperatures and under a pressure of 5—100 MPa; no strain hardening occurs in the material, even at slow deformation rates, because of its stable microstructure; Newtonian flow occurs, with a stress exponent of approximately unity; and the material has activation energy values for flow in the range 344—410 kJ·mol−1. Grain-boundary sliding and grain rotation, accommodated by viscous flow, might be the mechanisms of superplasticity for the present material. |
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Keywords: | deformation silicon nitride mechanical properties |
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