钛基氮化物硬质薄膜材料力学、热力学特性及致硬机理的研究

钛基过渡族金属氮化物硬质材料因具有高硬度、低摩擦系数、良好的耐腐蚀、抗氧化和抗摩擦性能等优点，在材料的装饰涂层、模具的保护涂层及微电子领域的扩散阻挡层等方面具有广泛的应用前景，已成为新材料领域的研究前沿和热点。本课题旨在采用基于密度泛函理论(DFT)的第一性原理方法，并结合从头算原子热力学方法，从理论上系统地研究钛基氮化物TiN 、TiAlN和TiCrN 硬质材料的力学、热力学特性及其致硬机理，阐明TiN 、TiAlN和TiCrN 体系的微观结构、电子结构特点和具有高硬度的本质原因，探寻钛基氮化物硬质材料的力学、热力学及动力学稳定性与高硬度之间的最佳结合点，揭示温度压强、膜层厚度以及Al 、Cr含量等因素对这类硬质材料的力学、热力学及其硬度特性的影响及其致硬机理，探寻改良钛基氮化物硬质材料性能的可能途径，以期为该类硬质材料在实验上的合成和工业上的应用提供理论依据和指导。

Transition-metal (TM) nitrides TiN,TiAlN and TiCrN films are considered as an important functional materials due to their rich variety of properties, such as high hardness,low friction coefficient, high-temperature resistance, superior oxidation andcorrosion resistance as well as good thermal stability. These properties are favorable for applications in the mold of protective coating, the adornment of the material coating, microelectronic devices and hard protective coatings for cutting tools. In the past twenty years, TiN,TiAlN and TiCrN films have inspired many experimental and theoretical investigations. Despite the success of sputter deposited transition metal nitrides thin films, there remains much uncertainty related to the correlations between the mechanical, thermodynamical properties and the doping concentration and the size of thin films. Also the hardness mechanisms of these materials is not clear. In current project, we will study the microstructure, electronic structure, the mechanical, thermodynamical properties and mechanisms of hardness of the TiN,TiAlN and TiCrN thin films using the first-principles calculations based on density functional theory (DFT) along with the ab initio atomistic thermodynamics method. Our purposes are to (1) elaborate the correlations between the mechanical, thermodynamical properties and the doping concentration and the size of thin films of TiAlN and TiCrN and hence obtain a better interplay between theory and experiment; (2) shed light on the mechanism of hardness of the thin films. The findings will rationalize the available experimental results well and enrich our understanding of functional properties of the TiN,TiAlN and TiCrN thin films. Moreover, this study will provide the theoretical insights for the application of TiN,TiAlN and TiCrN films and open a new way for the designing of new higher hardness coating materials.