基于微观结构演化的多尺度混杂颗粒增强铝基复合材料热变形行为及损伤机制

The interaction between the reinforcement and matrix during hot deformation is very complex for multiscale hybrid particle reinforced aluminum matrix composites, which hinders the process control of microstructure and damage in the thermoplastic processing. In order to solve the problem, theoretical analysis, numerical simulation and experimental testing are used in this research proposal. Specifically, the hot forming mechanism of multiscale hybrid particle reinforced aluminum matrix composites is studied, and the uniform constitutive relation of flow stress during hot deformation is established according to combined effect of the physical relation of microstructure evolution and strengthening mechanism of reinforcement. A simulation model of microstructure evolution embedded the effect of particle stimulated nucleation is constructed and the influence of multi-scale heterogeneous reinforcement on the matrix microstructure evolution is discussed. A discrete element numerical method is developed to predict the damage evolution of multiple microstructures and it is tried to reveal the damage mechanism of interaction between the microstructures of reinforcement-matrix-interface and microstructure defects. The response between the thermoplastic process parameters and the microstructure characteristic parameters is studied and the multi-objective optimization algorithm is used to realize the coordinated control of microstructure evolution and damage. This research can reveal the internal relationship among the evolution of microstructure, hot deformation behavior and damage mechanism, which provides a practical theoretical basis for shape and performance control of multiscale hybrid particle reinforced aluminum matrix composites in the thermoplastic forming.

多尺度混杂颗粒增强铝基复合材料的增强体与基体在热变形过程中的交互作用十分复杂，给其热塑性成形组织及损伤控制带来巨大的障碍。针对这一关键问题，本项目采用理论分析、数值模拟与实验测试有机结合的方式，研究多尺度混杂颗粒增强铝基复合材料的热变形机制，建立耦合微观结构演变物理关系与增强体强化机制的热变形流动应力统一本构关系；构建反映颗粒激发形核作用的微观组织演变仿真模型，阐明多尺度异质增强体对基体组织演变的影响机制；建立预测多重微观结构损伤演化行为的离散元数值方法，揭示增强体-基体-界面微观结构与微观缺陷交互作用损伤机理；确立复合材料热塑性成形工艺参数与微观组织结构特征参量的响应关系，通过多目标优化算法实现微观组织结构与损伤缺陷协同控制。本项研究能够揭示微观结构演化规律与材料热变形行为、损伤机制内在依存联系，为多尺度混杂颗粒增强铝基复合材料热塑性成形控形控性提供切实的理论依据。

我国在航空航天及武器装备等领域对轻质高强高韧铝基材料构件的需求日益迫切。常规的单相陶瓷或金属化合物颗粒增强铝基材料在性能上已无法满足使役要求。因此发展新型多尺度混杂颗粒增强铝基复合材料及其成形技术，利用多相增强体跨尺度协同强化效应，充分发挥多种增强体的优势并有效集成，进而实现铝基复合材料构件力学性能的有效提升，具有重要的研究意义。针对多尺度混杂颗粒增强铝基复合材料在高端构件热塑性成形制造上的迫切需求和复杂微观结构导致铝基复合材料热塑性加工控形控性难以实现的关键问题，本项目开展了多尺度混杂颗粒增强铝基复合材料热变形流动应力行为，变形组织演化机理，复合材料损伤机制及微观组织结构控制等方面的研究。通过研究建立了多尺度混杂颗粒增强铝基复合材料微观结构演变与强化机制统一的流动应力本构关系；基于组织特征关联的宏微观多尺度模型，模拟了复合材料热变形组织与微观缺陷的演化过程；结合仿真建模和数值优化方法，创建了多尺度混杂颗粒增强铝基复合材料热塑性成形微观组织结构与损伤缺陷协同控制策略，取得的研究结果揭示了多尺度增强体局域激发再结晶形核作用，明晰了微观结构与初始缺陷交互作用下损伤演化机制，实现了多尺度混杂颗粒增强铝基复合材料热变形加工过程中的形性控制。本项目研究成果可显著提高铝基复合材料组织性能，为高性能铝基复合材料热塑性成形精确化控制提供科学途径，有效满足国家高端装备对先进铝基复合材料制造的紧迫需求。