期刊
ACTA MATERIALIA
卷 60, 期 4, 页码 1570-1575出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2011.11.053
关键词
Nanocomposites; Ceramics; Mechanical properties; Optical properties
资金
- Defense Advanced Research Projects Agency (DARPA)
In response to a need for improving the mechanical properties of optically transparent ceramics, the nanocomposites approach is used to strengthen transparent magnesium-aluminate spinel with Si3N4 nanodispersoids. The as-processed nanocomposites are found to be >70% transparent in the critical infrared wavelength range of 3-4.5 mu m. Mie scattering combined with absorption by the Si3N4 nanodispersoids explains quantitatively the IR transmission behavior of these nanocomposites. The nanocomposites are also found to be transparent in the visible region. Upon heat treatment (1000 degrees C for 4 h in air), the optical properties of the nanocomposites remain unchanged. However, the heat treatment results in a 29% increase in the average strength, accompanied by almost doubling of the Weibull modulus, and an 85% increase in the indentation toughness. The improvements in mechanical properties after the heat treatment in these nanocomposites are explained qualitatively, based on generally accepted arguments involving surface-oxidation-induced surface compression and flaw-healing. While further work is needed to fully understand and exploit these effects, this first report on transparent nanocomposites could have broad implications for the creation of mechanically robust, transparent ceramics of the future. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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