Computer simulation of grain growth and Ostwald ripening in alumina-zirconia two-phase composites
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
The kinetics of grain growth and Ostwald ripening in Al{sub 2}O{sub 3}-ZrO{sub 2} two-phase composites was systematically investigated using two-dimensional (2-D) computer simulations, based on a diffuse-interface field model. Using average values for the experimentally measured ratios of the grain boundary energies to the interphase boundary energy as the input, the predicted 2-D microstructural features and their evolution are in excellent qualitative agreement with experimental observations on 2-D cross sections of 3-D Al{sub 2}O{sub 3}-ZrO{sub 2} two-phase composite microstructures. It was found that the coupled grain growth in Al{sub 2}O{sub 3}-ZrO{sub 2} composites is controlled by long-range diffusion and the average size (R{sub t}) as a function of time (t) follows the power-growth law, R{sub t}{sup m} {minus} R{sub 0}{sup m} = kt with m = 3, which is independent of the initial microstructures and volume fractions of the two phases. The predicted variation of the kinetic coefficient (k) on the volume fraction follows a trend similar to that experimentally measured through the entire range of volume fractions. The scaling of grain size distributions is observed at a given volume fraction, i.e., they are time-invariant in the steady state. However, the characteristics of size distributions vary with the initial microstructures and the volume fractions. The relationship between matrix grain size and second-phase grain size is discussed.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States)
- OSTI ID:
- 529540
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 7 Vol. 80; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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