Phase-Field Simulation Of The Grain Growth And Its Kinetic

Grain growth, which is widely observed in metals, alloys, ceramics and other polycrystalline materials , has significant effect on the material's properties. Investigation on the process and the kinetics of the grain growth is of both theoretical and practical significance. In recent years, computer simulation has become an effective means in the field of materials design and microstructure evolution with the development of computational materials science. Thus, in present thesis, the grain growth process under the conditions of normal single phase, anisotropic in grain boundary energy, two phase and the second-phase particles pinning are simulated by means of the phase-field method. The microstructural evolution, the kinetics of the grain growth and the topological evolution in polycrystalline are also systematically analyzed in detail. The main conclusions are as follows:1. The microstructural evolution and the topological evolution in polycrystalline under different conditions can be really reappeared by the phase field method. The simulated results are in greatly accordance with experimental results.2. In the case of the normal grain growth, the simulated results indicate the angle between two adjacent grains tends to 120°, the average area of grain is linear with the evolution time, and the distribution of normalized grain size is time independent. The grain growth velocity is in direct proportion to the coefficient of the grain boundary energy k^0.5 and inverse proportion to the parameter r^1.5.3. In the anisotropic system, the low energy boundary is stable, while the high energy boundary is unstable and grows faster. Moreover, the distribution of the grain size is non-uniform. The scales of the grain size and the distributions of edges were broadened than that of the isotropic system. And the distributions of the average grain area are different in these two systems. With the increasing of the grain boundary energy anisotropy, the grain grows slowly and the uniformity of the grain structure decreases.