COMPUTER-SIMULATION OF ANISOTROPIC GRAIN-GROWTH IN CERAMICS

Anisotropic grain growth in ceramics has been simulated by a Monte Carlo computer model. Microstructures, similar to experimental ones, were obtained and the influence of the energy anisotropy and the number of anisotropical grains on microstructure development were studied. It was shown that a single grain with higher energy in one direction, embedded in a matrix of grains with the isotropic boundary energy, grows anisotropically with a nearly constant rate. The growth rate is linearly proportional to the energy anisotropy of the grain. The aspect ratio increases with the cube root of time. Faceted grain boundaries were simulated. Microstructures with less than 50% of anisotropic grains develop, after a short time, a bimodal grain size distribution. At this point, the mean aspect ratio of anisotropic grains reaches a maximum. The heights of the maxima are proportional to the energy anisotropy and inversely proportional to the fraction of anisotropic grains. Weighted aspect ratio distributions and their mean values agree well with experimental data.