镁合金界面构建与位错改性的协同调控及强塑性机制

针对国家对装备轻量化的重大需求，以及为了促进镁合金及其复合材料在汽车、航空航天等领域的广泛应用和提升镁合金产业链，本项目通过第一性原理计算从原子尺度出发设计和优化陶瓷相与镁合金界面的结构特征。在此基础上，在镁合金中加入多种异质陶瓷强化相，构建不同性质的多重界面结构。通过界面与位错及孪晶的交互作用而改变层错和空位等界面组织缺陷，促使基面、非基面的位错及孪晶发生演变，在界面有效传递应力的同时，提高位错密度和改变界面晶体取向，促使更多位错在室温沿着非基面滑移和攀移以及拉伸孪晶形成，从而显著提高镁基复合材料的强度和塑性，据此提出陶瓷颗粒强化镁基复合材料的强塑性机制和有效界面结构特征，并建立和完善相应的理论模型，突破镁基复合材料强度高而塑性差的技术瓶颈，并解决复合材料界面设计的共性基础科学问题。本项目的完成，将推动我国轻质镁合金材料的快速发展，也为其他金属基复合材料性能的提升提供理论依据和技术指导。

In response to a major national requirement for the equipment lightweight, and in order to promote the wide application of magnesium alloys and their composites in the automobile, aerospace and other fields and to improve magnesium alloy industry chain, designation and optimization of the ceramic phase/Mg matrix alloy interface structures are derived from first-principles calculations on the atomic- scale in this project. On this basis, the multiple interface structures with different nature are constructed by adding multiple heterogeneous ceramics reinforcements into Mg alloy matrix. The stacking fault, vacancy and other interface defects are changed by the interaction between interface, dislocation and twin, and then the evolutions of dislocation in basal plane and non-basal plane and twin are caused. Therefore at the same time of effective stress transfer on the interface, dislocation density is increased and the interface crystal orientation is changed, and more dislocations are enforced to slip and climb along non-basal plane, and tensile twins are also formed at the room temperature. As a result, the strength and plasticity of Mg-based composites are significantly improved. And the strong plasticity mechanism and the interface structure characters of ceramic particle reinforced Mg-based composites are proposed and the corresponding theoretical models are also established and improved. Then the technical bottlenecks about high strength and low plasticity for ceramic particle reinforced Mg-based composites are broken, and the common foundational science problems about the interface designation of the composites are solved. Completion of the project will promote the rapid development of light magnesium alloy materials in China, and also provide the theoretical basis and technical guidance for the performance improvement of other metal matrix composites.