Influence of Grain Size on the Tensile Creep Behavior of Ytterbium-Containing Silicon Nitride

Published

March 1, 2004

Author(s)

Sheldon M. Wiederhorn, A R D Lopez, William E. Luecke, Michael J. Hoffmann, B Hockey, J French, D C. Yoon

Abstract

The effect of grain size on the tensile creep of silicon nitride is investigated on two materials, one containing 5 % by volume Yb2O3, the other containing 5 % by volume Yb203 and 0.5 % by mass Al2O3. Annealing of the alumina-free silicon nitride increased the grain size by a factor of two. This increase did not affect the creep rate; the grain size exponent of the creep rate differed little from zero, p=0.25 1.32 (95 % confidence level). This finding supports the more recent theories of creep for which p = 0 or -1 and rejects the more classical theory of solution precipitation. In contrast to the alumina-free material, annealing the alumina-containing material did not increase the grain size. Although the grain size did not increase, the annealed alumina-containing material crept 20 to 80 times slower than the unannealed material. Apparently, the chemical composition of the grain boundaries is more effective in controlling creep rate than is grain morphology.

Citation

Journal of the American Ceramic Society

Volume

87

Issue

No. 3

Pub Type

Journals

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Keywords

grain size, microstructure, silicon nitride, tensile creep behavior

Citation

Wiederhorn, S. , D, A. , Luecke, W. , Hoffmann, M. , Hockey, B. , French, J. and Yoon, D. (2004), Influence of Grain Size on the Tensile Creep Behavior of Ytterbium-Containing Silicon Nitride, Journal of the American Ceramic Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=850057 (Accessed April 24, 2024)