Establishing relationships between the electron work function and mechanical and tribological properties towards advanced materials design

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Conventional metallurgical rules have been successfully used in materials design for centuries but limitations are still there. Many expensive and time-consuming trial-and-error experiments are needed before a new material is successfully developed. With technological advances, it has been possible to develop more fundamental approaches for advanced materials design with higher accuracy and efficiency. It has long been a dream to design structural and tribological materials based more on the electron behavior, since the mechanical strength of a material is essentially governed by electronic interactions. However, the electronic theory of materials is so complicated and not easy to be applied by materials engineers for materials design. Recent studies have shown that it is feasible to a simple parameter, electron work function (EWF), to correlate the mechanical properties of materials with their electron behaviour. As an example, the Young's modulus of metals (E) exhibits a sixth power relation with their work function. However, although some correlations between materials properties and the work function have been observed, mechanisms behind are not well understood. In particular, how to use the concept of EWF effectively in guiding materials design is far behind the fundamental research on EWF itself. The main obstacle is the lack of established correlations between EWF and material properties and solid theory. Such correlations and relevant theory are highly desired not only for fundamental research but also for advanced materials design. The objectives of this research are 1) to understand and establish the correlations between EWF and mechanical and tribological properties; 2) to develop theoretical models to quantify the correlations; and 3) to explore applications of EWF in mechanical and tribological processes. The ultimate goal of the proposed research is to build foundations for effective incorporation of the electron behavior via a feasible parameter, electron work function, in advanced materials design and characterization.