The Zener pinning effect with growing second-phase particles in Al2O3-ZrO2 composite systems were studied by two-dimensional (2-D) computer simulations using a diffuse-interface field model. In these systems, all second-phase particles are distributed at grain corners and boundaries. The second-phase particles grow continuously, and the motion of grain boundaries of the matrix phase is pinned by the second-phase particles which coarsen through the Ostwald ripening mechanism, i.e., long-range diffusion. It is shown that both matrix grains and secondphase particles grow following the power-growth law, Rt m - R0 m = kt with m = 3. It is found that the mean size of the matrix phase (D) depends linearly on the mean size of the second-phase particles (r) for all volume fractions of second phase from 10% to 40%, which agrees well with experimental results. It is shown that D/r is proportional to the volume fraction of the second phase (f) as f -1/2 for a volume fraction less than 30%, which agrees with Hillert and Srolovitz's predictions for 2-D systems, while experimental results from 2-D cross sections of three-dimensional (3-D) Al2O3-rich systems showed that either a f -1/2 or a f -1/3 relation might be possible. It is also found that D/r is not proportional to f -1/3 and f -1 in 2-D simulations, which suggests that the Zener pinning effect can be very different in 2-D and 3-D systems.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of the American Ceramic Society|
|State||Published - Mar 1998|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry