循环复合镦压制备Mg2Si原位增强超细晶镁基复合材料的研究

We select Mg-Al(Zn)-Si alloys with different compositions, take advantage of superior properties of Mg2Si and in-situ formation during solidification process under favorable conditions, apply cyclic compound upsetting(CCU) severe plastic deformation for microstructure refinement and homogenization, and fabricate in-situ Mg2Si-reinforced magnesium matrix composite with ultrafine uniform microstructure. We will investigate the effects of initial microstructure of the billet, and CCU processing parameters including temperature and number of passes on composite microstructure including matrix grain morphology and size, secondary phase Mg2Si particle morphology, size, quantity and distribution, Mg2Si/Mg interface, and microstructure homogeneity; and investigate temperature field, flow field, stress and strain field, and flow rheology, and reveal the microstructure and texture evolution of the composite during CCU, and illustrate the ultrafine homogeneous microstructure formation mechanisms, and evaluate the tensile strength, Vickers hardness, and wear resistance mechanical properties, and establish relationships among alloy composition, billet microstructure, fabrication parameters, composite microstructure, and mechanical properties, and lay a solid foundation for the applications of in-situ Mg2Si-reinforced magnesium matrix with ultrafine and homogeneous microstructure. The proposed research will open up a new way for the development high performance magnesium alloys and magnesium-based composites, and their relevant fabrication processing technologies.

选择Mg-Al(Zn)-Si合金成分，利用Mg2Si的优异特性和在凝固过程中原位形成的有利条件，采用循环复合镦压大塑性变形技术，细化和均匀组织，制备Mg2Si原位增强的超细均匀组织镁基复合材料。研究坯料原始组织、循环复合镦压工艺参数(镦压温度、镦压道次等)对复合材料组织的影响规律，包括基体晶粒形貌、大小，第二相Mg2Si的形貌、大小、数量和分布，Mg2Si/Mg界面结构，组织均匀性；研究循环复合镦压过程中复合材料的温度场、流场、应力场、应变场和变形流动行为；弄清循环复合镦压过程中复合材料组织、织构的演化规律，揭示复合材料超细、均匀组织的形成机制；评价复合材料的拉伸、硬度、耐磨等性能，建立合金成分、坯料组织、制备工艺与复合材料组织、性能之间的关系，为Mg2Si原位增强均匀、超细组织镁基复合材料的应用奠定基础。本研究将为高性能镁合金和镁基复合材料开发及其制备加工技术开辟新途径。

Mg2Si熔点高，弹性模量高，热膨胀系数低，Mg2Si/Mg复合材料很有潜力作为结构材料使用。本项目采用循环复合镦压大塑性变形技术制备了Mg2Si原位增强的超细均匀组织镁基复合材料，研究了坯料原始组织、循环复合镦压工艺参数对复合材料组织的影响规律，分析了循环复合镦压过程中的温度场、流动场、应力场、应变场和变形流动行为，评价了复合材料的拉伸、硬度、耐磨等性能，弄清了循环复合镦压过程中复合材料组织、织构的演化规律，揭示了复合材料超细、均匀组织的形成机制，建立了合金成分、坯料组织、制备工艺与复合材料组织、性能之间的关系，为Mg2Si原位增强均匀、超细组织镁基复合材料的应用奠定了基础，为高性能镁合金和镁基复合材料开发及其制备加工技术开辟了新途径。