为满足我国汽车、航空航天等领域对轻质高性能镁合金材料的迫切需求，提高传统镁合金材料的强度和塑性，降低材料制备成本，本项目采用精确设计的镁合金无溶剂熔炼系统，以气－液－固反应机制为依据，通过原位反应方法在镁合金中生成均匀分布、稳定有效，且与基体结合良好、界面清洁的AlN纳米颗粒强化相，从而稳定获得具有工程应用价值，铸件拉伸强度高于300MPa，延伸率40％左右，且成本低廉、工艺简单的新型纳米颗粒增强镁基复合材料。在此基础上，研究纳米颗粒原位生成和均匀分布的热力学、动力学及溶质条件，通过研究纳米颗粒体积分数、尺寸和分布等对基体组成及晶粒大小、形貌的影响，揭示该复合材料高强高塑性的微观组织本质和强韧化机制，建立可预测纳米颗粒强韧化的理论模型。上述研究工作将从材料制备技术和性能理论控制两个方面，优化组织和调控材料力学性能，为新型高强高塑性纳米颗粒增强镁基复合材料的制备和发展提供理论依据和技术指导。

In order to meet the urgent demands for light-weight high-performance magnesium alloy materials in the fields of automobile and aerospace etc industries, and to improve the strength and plasticity of the conventional magnesium alloys and to reduce the cost of material processing, a precisely designed magnesium alloy melting system without the flux addition is adopted in this project. In terms of gas-solid-liquid reaction mechanism, uniformly distributed, stable and effective AlN nanoparticles as reinforcement phase having the clear and good compatibility interface with the matrix, are formed in Mg-based alloys by in-situ synthesizing methods. Sequentially, a new in-situ nanoparticle reinforced Mg-based composites can be prepared, which have practical engineering value, the as-cast tensile strength of above 300MPa, the as-cast elongation of about 40%, low cost and simple preparation process. On this basis, thermodynamics, kinetics and solute conditions of nanoparticles in-situ forming and uniform distribution will be proposed. By studying the effect of volume fraction, size and distribution of nanoparticles on the matrix alloy composition, grains size and microstructure morphology, the microstructure nature and the strengthening and toughening mechanism of nanoparticle reinforced Mg-based composites will be revealed and a theoretical model to predict the strengthening and toughening effect of nanoparticles will be built. The above researches will optimize the composites microstructure and control mechanical properties of the composites from two aspects of the composite preparation technology and theoretical control of the performance, which will provide the theoretical foundation and technical guidance for the preparation and development of novel Mg-based composites with high strength and high plasticity.