AlSi10Mg/SiC复合梯度材料点阵结构的激光选区熔化成形机理研究

Aluminum matrix components with lattice structure are characterized by ultra lightweight, high specific strength/stiffness, as well as a capacity of shock absorption, heat dissipation, sound absorption and so on. They play a dual role of structure and function and have great application potential in the field of hypersonic vehicle and high temperature engine. A single aluminum alloy component with lattice structure manufactured by traditional methods cannot meet the functional requirements in the extreme environment, while gradient composite components with lattice structure could be applied to solve the smooth transition problem of interfacial microstructure and properties of dissimilar metals. In this project, selective laser melting technology with a multi-material hopper and double laser was applied to integrally form AlSi10Mg/SiC gradient composites with lattice structure. The in-situ formation mechanisms of AlSi10Mg/SiC gradient composites with lattice structure would be investigated as well as the interface bonding and deformation control mechanisms. The relationship between the composite material proportion, SLM coupling process and lattice structure performance could be established provide theoretical support for the integrated manufacturing of high performance AlSi10Mg/SiC gradient composites with lattice structure. The implementation of this project could laid a foundation for the realization of lightweight design and safety applications of similar high-flying aircraft.

铝基点阵结构具有超轻、高比强/比刚度等优良机械性能以及减震、散热、吸声等特殊性质，兼具结构和功能双重作用，在高超飞行器与高温发动机领域具有重大的应用潜力。传统方法制造的单一铝合金点阵结构无法满足极端环境下的功能要求，梯度材料点阵结构是解决异种材料互联界面组织与性能平稳过渡难题的关键。本项目拟采用激光选区熔化技术(SLM)耦合多材料漏斗落粉机构和双激光在线退火整体成形AlSi10Mg/SiC复合梯度材料点阵结构，系统研究AlSi10Mg/SiC梯度材料点阵结构的SLM原位成形机理、界面结合机理及形变调控机制，建立复合材料配比-SLM耦合工艺-点阵结构性能之间的关系模型，形成SLM成形AlSi10Mg/SiC复合梯度材料点阵构件的工艺控制理论，为高性能AlSi10Mg/SiC复合梯度材料点阵结构的整体制造提供理论支持，以实现类似高超飞行器的轻量化设计与安全应用。

点阵材料具有超轻、高比强、减震、散热、吸声等特殊性质，在航空/航海/航天领域可以实现轻量化的同时提高承载效率和功能效率等。金属点阵结构材料多采用轻质铝合金，但目前的研究主要集中在单一铝合金的平面金属点阵结构。对于类似高超飞行器的隔热铝合金点阵结构，由于要求点阵结构与外层C/SiC复合材料防热层和铝合金基体的整体互联，互联界面的组织与性能的平稳过渡难以保证，往往是失效的主要途径之一。因此，探索铝合金/SiC复合梯度材料点阵结构的整体成形工艺与界面结合理论，是指导类似高超飞行器中关键构件轻量化设计与安全应用的关键。本项目重点围绕AlSi10Mg/SiC复合材料梯度点阵结构的激光增材制备与成形开展控形与控性方面的基础研究。项目主要完成SLM原位制备不同SiC含量的AlSi10Mg/SiC复合材料的工艺参数优化，并对金属/陶瓷界面进行深入分析；研究热处理对AlSi10Mg/SiC复合材料组织性能的调控机制；研究材料分配与体积分数对点阵结构在载荷作用下的变形行为与破坏机制的影响规律，提出采用SLM成形梯度材料点阵结构和多材料点阵结构的方法；建立复合梯度材料点阵结构对热阻性能与机械性能的影响规律模型，实现二者性能的最优设计与制造。研究发现退火热处理可使AlSi7Mg残余应力降低87.6%，组织均匀，晶粒细化，塑性提升；nano-SiCp的添加可以提升AlSi7Mg力学性能和电化学腐蚀性能，强化机制主要包括固溶强化、细晶强化、原位反应产生的少量nano-Al4C3强化以及析出相与位错环的协同强化；AlSi10Mg/SiC复合材料改善了SLM过程中点阵结构的粘粉现象，提高了成形精度和抗压性能；与均质点阵结构相比，梯度材料点阵结构在压缩过程中呈逐层断裂特点，具有更高的屈服强度和弹性模量，断裂应变明显缩短；受柚皮泡沫结构启发，提出了圆形、方形、椭圆形连接杆的多面体点阵结构，发现CSM结构是兼具传热和能量吸收的最好选择。