材料微结构演化的相场模拟

材料的各种宏观性能与其内部的微观结构密切相关，如何通过控制材料微结构的分布来提高其性能指标一直是工程界与学术界广泛关注的课题。由于场变量在界面的突变，传统的基于局部理论的突变界面模型在描述材料微结构演化方面存在一定的困难。基于非局部理论的相场法采用扩散界面的概念来描述界面，避开了理论上描述突变界面的困难，在模拟材料内部任意的组织形态和复杂的微结构演化方面具有独特的优点。本文首先介绍相场法的热力学理论基础，包括自由移动边界问题、扩散界面模型、非局部能量泛函、相场动力学方程及其常用求解方法。然后重点介绍铁电、铁磁和多铁性材料微结构演化的相场模拟，同时简要介绍相场法在软物质和锂离子电池材料微结构演化模拟中的应用,最后给出总结和展望。

Phase Field Simulations of Microstructure Evolution

The macroscopic properties of materials are highly dependent on microscopic structures. The enhancement of material performance by microstructures has drawn much attention in both industry and academia. Due to the discontinuity of field variables at the interface, the sharp interface model based on the local theory has the difficulty in predicting the microstructure evolution of materials. The phase field method based on the nonlocal theory employs a diffusive interface concept to model the interface, which exhibits several advantages over sharp interface model in predicting the arbitrary and complex microstructures of materials. In this paper, we firstly introduce the fundamental theory of phase field method, which includes the free boundary problem, diffusive interface model, nonlocal free energy function, the phase field governing equation and its numerical solution. Secondly, we present some research work on the phase field simulations of ferroelectric, ferromagnetic and multiferroic materials, with a brief introduction to phase field simulations of the microstructure evolution of softer mater and Li-ion battery. Finally, we give a summary and propose a few research topics of phase field simulations worthy to be investigated.