Computer simulation of grain growth using a continuum field model

The kinetics of grain growth in two-dimensions (2-D) were investigated by computer simulations based on a continuum diffuse-interface field model. In this model, a polycrystalline microstructure is described by many orientation field variables whose temporal and spatial evolutions can be obtained by solving the time-dependent Ginzburg-Landau (TDGL) equations. It is found that the time dependence of average grain radius R̄ follows the kinetic law: R̄^m_l - R̄^m₀ = kt with m = 2.0 in the scaling regime, in agreement with most of the previous simulation and theoretical results obtained using sharp-interface models. It is shown that the Louat's function provides a reasonable fit to the grain size distribution obtained from the simulation. In contrast to the general belief that 4-and 5-sided grains transform to 3-sided before their disappearance in 2-D grain growth, we found ample evidence that 4-sided and 5-sided grains may directly evolve to a region of disordered material, whose size is on the order of the grain boundary thickness and whose boundaries with neighbours are not well defined, and then disappear. The dependencies of grain growth kinetics on the computational cell size, the discretizing grid size, grain boundary width, as well as the number of field variables were critically examined.