Simulation Of The Influence Of Inter Facial Anisotropic On The Microstructure Evolution By Phase-field Approach

It is well known that the properties of materials largely depend on their microstructure, while the interface plays a very important role in the microstructure evolution process. For most of the materials in the real world, interfacial anisotropic cannot be ignored in their preparation process (such as freezing, aging, grain growth, etc.). Moreover, in-depth understanding of the interfacial anisotropic in microstructure evolution helps us to optimize the material preparation process, enhances the performance of existing materials, and even designs new materials. However, with experimental means alone, one cannot describe interfacial anisotropy quantitate. Thus, we often use computer simulation approach in conjunction with key experiments to achieve this purpose.This work chooses the Al-Cu alloy during aging and grain growth processes as the research object. We systematically study the influence of interfacial anisotropic on the microstructure evolution during corresponding materials process by three-dimensional (3-D) phase-field simulation approach. Our work provides a strong theoretical basis for the process optimization and design of new materials. The important research results obtained in this paper are as follows,1) We construct a3-D phase-field model which involves the contribution of elastic energy base on the work of Vaithyanathan. The model is used to simulate the age hardening of Al-2%Cu alloy at low temperature (200～250℃), and the results are compared with the ones from2-D simulations and experimental data mentioned in the literature. Simulation results show that both the properties of interfacial energy and elastic energy determine the morphology of θ’precipitate. This work also calculates the average thickness, length and aspect ratio of θ’precipitate variation versus aging time via statistical analysis for simulation results of microstructure evolution. 2) We use a phase-field model based on Moelans to implement3-D simulations for both isotropic and anisotropic systems via some special treatments to study to influence of low-angle grain boundaries (LAGB) on the grain growth process. A reduced one-dimensional variable θ is introduced to represent the misorientation in3-D space, which can greatly simplify the complex microstructure simulation. The simulation results of grain morphology and growth kinetics from isotropic and anisotropic systems are compared. Through the comprehensive comparisons we conclude that the conclusions that the LAGB reduces the growth rate in anisotropic system compared to isotropic system.