纳秒脉冲激光诱导非晶合金表面微/纳米结构形成机理研究

Surface micro/nanostructures play a critical role for enhancing the applications of metallic glasses in industrial catalysis, biomedical engineering, superhydrophobicity and so on. For the observed surface hierarchical micro/nanostructures and nitride phase generated during the interaction between nanosecond pulsed laser, Zr-based metallic glass (MG) and nitrogen gas, investigations are implemented to reveal their formation mechanisms and effects on the mechanical performances, respectively. Accordingly, a method for efficient and controllable fabrication of large-area complex hierarchical micro/nanostructures on Zr-based MG surface and a method for adjusting mechanical performances of Zr-based MG are developed. By comparative experiments, theoretical and finite element analysis, emphases are focused on the effects of laser irradiation parameters on surface/subsurface micro/nanostructures, laser-MG-nitrogen gas interaction processes, the dependence between surface hydrophobicity and micro/nanostructures, and the coupling effects of laser irradiation itself and nitride phase on the micro-scale plastic deformation behaviors and mechanical performances of Zr-based MG. According to the aforementioned analyses, the relationship between laser irradiation, surface micro/nanostructures and hydrophobicity as well as the relationship between laser irradiation, subsurface microstructures and mechanical performances is revealed, and thus, targeted adjustment of Zr-based MG surface micro/nanostructures and mechanical performances can be achieved. The results obtained in this project contribute to the in-depth understanding of complex physical mechanisms in laser-material interaction, and they are of great significance for improving the functional and structural applications of MGs.

表面微/纳米结构对于增强非晶合金在工业催化、生物医学、超疏水等方面的应用起到关键作用。针对纳秒脉冲激光—锆基非晶合金—氮气交互中观察到的表面分层微/纳米结构和氮化物相，研究其形成的物理机制及对力学性能的影响，进而发展一种锆基非晶合金表面大面积复杂分层微/纳米结构的高效、可控制备方法和力学性能调控方法。通过对比试验并结合理论和有限元分析，着重研究辐照参数对非晶合金表面/亚表面微结构的影响，研究激光—非晶合金—氮气的交互作用过程，研究表面疏水性与微/纳米结构之间的依赖关系，研究激光辐照本身与氮化物相对非晶合金微尺度塑性变形行为与力学性能的耦合影响，揭示激光辐照—表面微/纳米结构—疏水性以及激光辐照—亚表面微结构—力学性能之间的相互关系，实现锆基非晶合金表面微/纳米结构与力学性能的精准调控。项目研究成果有助于激光—材料之间复杂物理交互机制的理解，对促进非晶合金的功能和结构应用具有十分重要的意义。

非晶合金由于具有优异的力学、物理和化学性能，是非常有潜力的新型材料。然而，大多数非晶合金拉伸塑性低，常呈脆性断裂，限制了其作为结构材料的应用。另一方面，高硬度、耐磨性和耐蚀性为非晶合金作为表面功能材料的应用提供了基础。在非晶合金表面制备微/纳米结构以及进一步提高其表面硬度，将丰富其表面功能应用。本项目通过研究纳秒脉冲激光—非晶合金交互作用过程，阐明了氮气内纳秒激光辐照诱导锆基非晶合金表面分层微/纳米结构的形成机理，在此基础上发展了一种非晶合金表面大面积微/纳米结构高效、可控制备新方法；揭示了激光辐照参数—表面微/纳米结构—亲/疏水性等之间的相互关系，实现了非晶合金表面亲水/输水性能调控；揭示了纳秒激光辐照本身对非晶合金表面的软化作用与机理，并在此基础上研究获取了纳秒激光辐照与氮化相引入对非晶合金表面力学性能的耦合影响与作用机制，进而发展了一种在氮气氛围内通过纳秒激光辐照调控非晶合金表面力学性能的新方法，目前已实现锆基非晶合金表面硬度提升3倍。作为上述主要研究工作的基础或拓展，项目实施过程中还一并研究了压痕诱导非晶合金剪切带与锯齿流变的关联性、非晶合金对低功率密度激光辐照的响应特性、压痕耦合抛光制备非晶合金表面微/纳米结构、纳秒激光辐照制备非晶碳表面微结构等相关内容。项目研究成果有助于激光—材料之间复杂物理交互机制的理解，同时为非晶合金表面微/纳米结构化与力学性能调控提供了新的技术手段，对推动非晶合金的功能与结构应用具有十分重要的意义。