Development of an electron work function-based novel methodology for designing advanced tribo-materials

材料科学和工程在开发理论和方法以提高材料的抗失效能力方面有着悠久的历史。微结构工程在材料设计中起着至关重要的作用。然而，微观结构特征并不总是为裁剪材料提供明确的线索。随着应用需求的增加，不仅在通常情况下，而且在极端情况下，材料设计也被要求依赖于更基本的原则。该项目旨在开发新的结构材料设计方法，重点是建立在可行的电子基础上的摩擦材料。材料的本征性质从根本上由它们的电子行为决定，电子行为决定着原子键的强度和延展性。长期以来，人们一直致力于基于量子力学将材料的力学性质与其电子态相关联，然而，这在结构材料设计中的使用是复杂的。为了以可行的方式进行材料分析和设计，迫切需要有简单但基本的参数来反映材料的电子行为。申请人小组对电子功函数(EWF)进行了广泛的研究，并证明EWF与许多材料性质相关，是指导裁剪材料的一个有前途的指标。然而，材料的性能不仅取决于材料中单个相和颗粒的性能，而且还取决于其微观结构。在具有不同EWF的多晶材料中，当第二相接触时，为了建立热力学平衡，会发生电子转移。这些都会影响EWF分布，从而影响整体性能。因此，了解微观结构成分如何影响整体EWF及其与整体或全局材料性能的关系，对于开发新的现实材料设计方法具有重要意义。这是这个新的Discovery项目提出的主要研究目标或*长期研究目标*，这与申请者之前的Discovery项目不同，后者侧重于EWF与纯金属和均匀*固体溶液的性质之间的*相关性。该项目将包括以下内容：1)研究微观结构成分，包括晶粒度、取向、晶界和第二相(尺寸、形态、性能和界面)如何影响多晶多相材料的局部和全局EWF；以及2)研究EWF和多相材料性能之间的相关性，以开发基于EWF的材料设计和剪裁的途径或方法，重点是摩擦材料。

Materials science and engineering have a long history of developing theories and approaches to improve materials for enhanced resistance to failure. Microstructure engineering plays a crucial role in material design. However, microstructural features do not always provide clear clues for tailoring materials. With increased demands for applications under not only usual conditions but also extreme ones, material design has been required to rely on more fundamental principles. This project is proposed to develop new methodologies for structural material design with emphasis on tribo-materials on a feasible electronic base. Intrinsic properties of materials are fundamentally determined by their electron behavior, which governs the atomic bond strength and ductility. Great effort has long been made to correlate mechanical properties of materials to their electron state based on quantum mechanics, which is, however, complicated to be used in structural material design. It is highly desired to have simple but fundamental parameters, which reflect the electron behavior of materials, for material analysis and design in a feasible manner. The applicant's group has conducted extensive studies on electron work function (EWF) and demonstrated that EWF is correlated to many material properties, and is a promising indicator for guiding tailoring materials. However, material properties are dependent not only on properties of individual phases and grains in a material but also its microstructure. When second phases in polycrystalline materials with different EWFs are in contact, there exists electron transfer in order to establish thermodynamic equilibrium. These affect EWF distribution and thus overall performance. Thus, it is of significance to understand how microstructural*constituents influence the overall EWF and its relationships with the*overall or global material properties towards the development of new*methodologies for realistic material design. This is the main goal or*long-term objective of research proposed in this new Discovery project,*which is distinct from that of applicant's previous Discovery project, which was focused on the*correlation between EWF and properties of pure metals and homogeneous*solid solutions. The followings will be included in the project: 1) studies on how microstructural constituents, including grain size, orientation, grain boundaries, and second phases (size, morphology, properties and interface), influence local and global EWFs of polycrystalline multiphase materials; and 2) studies on the correlation between EWF and properties of the multi-phase materials towards development of EWF-based approaches or methodologies for material design and tailoring with focus on tribo-materials.***********