MONTE-CARLO SIMULATION OF NORMAL GRAIN-GROWTH IN 2-DIMENSION AND 3-DIMENSION - THE LATTICE-MODEL-INDEPENDENT GRAIN-SIZE DISTRIBUTION

The phenomenon of normal grain growth in pure single phase systems is modeled with the Monte Carlo technique and a series of simulations are performed in 2- and 3-dimensions. The results are compared with natur al and experimental monomineralic rock samples. In these simulations v arious lattice models with different anisotropic features in grain bou ndary energy are examined in order to check the universality of the si mulation results. The obtained microstructure varies with the artifici al parameter T' in each lattice model, where T' means scaled temperatu re and controls thermal fluctuation on grain boundary motion. As T' (t hermal fluctuation) increases, the boundary energy anisotropy characte rizing each lattice model becomes less important for the evolution of the microstructure. As a result the difference in the grain size distr ibution among the lattice models, which is significantly large for low T', is reduced with increasing T'. The distribution independent of bo th the lattice model and the dimension is obtained at sufficiently hig h T' and is very close to the normal distribution when carrying out th e weighting procedure with a weight of the square of each grain radius . A comparison of the planar grain size distribution of the natural an d experimental rock samples with the 3-D simulation results reveals th at the simulations reproduce very well the distributions observed in t he real rock samples. Although various factors such as the presence of secondary minerals and a fluid phase, which are not included in the s imulation modeling, are generally considered to influence the real gra in growth behavior, the good agreement of the distribution indicates t hat the overall grain growth behavior in real rocks may still be descr ibed by the simplified model used in the present simulations. Thus the grain size distribution obtained from the present simulations is poss essed of the universal form characterizing real normal grain growth of which driving force is essentially grain boundary energy reduction th rough grain boundary migration.