纳米多孔金属的表面改性对其强韧特性的影响机制研究

Nanoporous metals are a class of novel nanomaterials with potential applications in many fields such as catalysis, sensing and filtration. The strength and toughness of nanoporous metal can be significantly improved through depositing even only atomic-layer thick coating on its surface. However, the underlying physical mechanisms are still open to further investigations. The major focus of this research is on studying the surface modification effects of nanoporous metal on mechanical properties by using multiscale method, which combines molecular dynamics (MD) simulation, finite element (FE) method and validation experiments. Firstly, the research will reveal the atomic-scale mechanisms of surface modification by analyzing the evolution of dislocations, such as dislocation emission, slip and reabsorption in the ligament of nanoporous metal via MD simulation. The mechanical parameters of the surface and core layers are extracted from the results by MD simulations and then feeded into the two-level hierarchical structural model for FE analysis. By means of multiscale simulations, the scaling laws for the mechanical properties of nanoporous metal with surface modification effects in terms of microstructural and coating parameters will be developed. Finally, the simulations for research on the electric-control of surface effects will be conducted, and a theoretical model will be established to describe the surface modification effects. The theoretical model will be checked by validation experiments. All results of the research project will provide a scientific foundation for describing the surface modification effects of nanoporous metal on mechanical properties in quantity.

纳米多孔金属是一类新型的纳米材料，在催化、传感和过滤等领域具有广泛的应用前景。通过在表面修饰仅原子层厚度涂层的表面改性途径，可显著提高纳米多孔金属的强韧特性，但其微观机制尚未明确。本项目拟采用以分子动力学和有限元数值模拟为主、验证性实验为辅的研究途径，对表面改性优化纳米多孔金属强韧特性的机制进行研究。主要内容包括：（1）通过分子动力学模拟，再现表面改性后的纳米多孔金属在外载下位错形核、滑移的全过程，在原子尺度明确表面改性调控的本质；（2）基于分子动力学的模拟结果，建立表面层和核心层的本构关系，并构造两级随机双连续网络的有限元模型，揭示表面改性的微观参数跨尺度逐级影响纳米多孔金属宏观力学性能的机制；（3）采用上述多级计算模型研究表面改性的电场二次调控，建立相关理论模型，并使用纳米压痕测试进行验证。通过以上研究，为纳米多孔金属强韧特性的表面改性调控提供定量表征。

纳米多孔金属是一类新型的纳米材料，在催化、传感和过滤等领域具有广泛的应用前景。通过在表面修饰仅原子层厚度涂层的表面改性途径，可显著提高纳米多孔金属的强韧特性，但其微观机制尚未明确。本项目采用以分子动力学和有限元数值模拟的研究途径，对表面改性优化纳米多孔金属强韧特性的机制进行研究。主要内容包括：（1）通过分子动力学模拟，再现表面改性后的纳米多孔金属在外载下位错形核、滑移的全过程，在原子尺度明确表面改性调控的本质；（2）基于分子动力学的模拟结果，建立表面层和核心层的本构关系，并构造两级随机双连续网络的有限元模型，揭示表面改性的微观参数跨尺度逐级影响纳米多孔金属宏观力学性能的机制。