Phase-field method is a density-based computational method at the mesoscale for modeling and predicting the temporal microstructure and property evolution during materials processes. The focus of this article is on connecting the most common phase-field equations to the very basic first and second laws of classical thermodynamics through rudimentary irreversible thermodynamics. It briefly discusses the relations of the continuum phase-field equations to their counter parts at the microscopic and atomic levels. It attempts to clarify the contributions of long-range elastic, electrostatic, and magnetic interactions to domain structure evolution during structural, ferroelectric, and ferromagnetic phase transformations by separating order parameter changes due to the presence of quasi-static fields and those arising from phase transformations. A few examples are presented to demonstrate the possibility of employing the phase-field method to provide guidance to designing materials for optimum properties or discovering novel mesoscale phenomena or new materials functionalities. The article ends with a brief perspective on a number of potential future directions on the development and applications of phase-field method beyond its traditional applications to structural alloys.

相场法是一种基于密度的中尺度计算方法，用于建模和预测材料过程中的时间微观结构和性能演变。本文的重点是通过基本的不可逆热力学将最常见的相场方程与经典热力学的第一定律和第二定律联系起来。它在微观和原子水平上简要讨论了连续相场方程与其对应部分的关系。它试图通过分离由于准静态场的存在和相变引起的有序参数变化，阐明长程弹性、静电和磁相互作用对结构、铁电和铁磁相变过程中畴结构演化的贡献. 提供了一些例子来证明使用相场方法为设计材料以获得最佳性能或发现新的中尺度现象或新材料功能提供指导的可能性。文章最后简要介绍了相场法在结构合金的传统应用之外的发展和应用的许多潜在未来方向。