镁基复合材料是理想的轻质高强结构材料，在航空、航天、交通等领域有广泛应用前景。微米颗粒和高体积比纳米颗粒增强的镁基复合材料面临高强度低韧性的困境，以低体积比纳米陶瓷颗粒和碳纳米管作为增强相的镁基纳米复合材料又无法获得理想的强度。我们通过仿生设计，成功制备了兼具高强度和高韧性的多级镁基纳米复合材料，突破了镁基复合材料的强韧性难题。然而，目前对多级镁基纳米复合材料的强韧化机理还缺乏研究。本项目将系统研究多级镁基纳米复合材料微观结构与力学行为之间的相互关系，解决多级镁基纳米复合材料的强化与韧化机理等关键科学问题，揭示硬相/软相协调变形机制和裂纹扩展规律，建立多级镁基纳米复合材料强韧性的理论预测方法，为开展镁基复合材料的性能优化设计奠定基础。本项目通过多级结构对镁基复合材料强韧性进行调控，在协调变形机制研究方面具有创新性。本项目的研究成果将拓展我们对多级结构材料塑性变形机理的认识。

Magnesium-based composites as a result of their low density and superior mechanical properties are potential candidates for applications in aerospace, automobile and transportation. Many attempts have been conducted in recent years towards the development of Mg-based composites reinforced by micro/nano particulates and carbon nanotubes with homogeneous distribution. The investigations have shown the strength-ductility trade-off dilemma in materials. We synthesized hierarchical magnesium-based nanocomposites with bioinspried microstructures, which presented outstanding strength and excellent ductility. The deep research should be conducted to explore the strengthening and toughening mechanism of the hierarchical magnesium-based nanocomposite. In this study, the deformation and failure behaviors of the hierarchical magnesium nanocomposites will be investigated at first. Then, the detailed mechanisms will be proposed to explain these mechanical behaviors base on the microstructure studies. Finally, we plan to establish a method to predict the strength and failure strain of the hierarchical magnesium nanocomposites. The project will expand our knowledge on the plastic deformation mechanism of materials with hierarchical microstructure.