汽车与航空航天等领域对轻质高强韧镁合金板材具有迫切需求。本项目针对制约镁合金板材商业应用的强度低刚度低塑性差的瓶颈问题，以低成本Mg-Al-Ca-Zn-Mn合金板材为研究对象，通过调控板材中的微纳米相种类、数量与分布，进而调控多尺度多相微观组织，构建破碎微米共晶相层/纳米析出相增强的再结晶/形变晶粒的层状结构，利用结构效应与不同微纳米相间的耦合效应，同时提高板材的强度刚度与塑性，开发具有多尺度多相层状分布特征的低成本高强韧镁合金板材。首先，通过合金设计、热处理与反向温度场轧制工艺参数调节，调控多尺度多相微观组织，研究微观组织的演变规律与调控机理，实现板材的组织性能可控制备；其次，多维原位研究多尺度多相微观组织对局域应变分布、形变微结构与断裂行为的影响规律，阐明结构效应与微纳米相耦合效应，揭示Mg-Al-Ca-Zn-Mn合金板材的强韧化机制，为低成本镁合金板材的强韧化设计与制备提供依据。

Automobile and aero space industries increasingly demand for the high strength and ductile Mg alloy sheets. However, low strength, low stiffness and poor ductility of the Mg alloy sheets limit their commercial applications. This proposal aims to solve this bottleneck by developing low-cost high strength and ductile Mg-Al-Ca-Zn-Mn alloy sheets. The micro/nanometer phases in the alloy sheet will be controlled so as to tailor the multi-scale multi-phase microstructure. Layered structure consisting of micro-sized fractured eutectic phases / nano-sized precipitates reinforced dynamically recrystallized grains / worked grains forms then the strength, stiffness and ductility of the alloy sheets will be simultaneously improved due to the structure and coupling effects of the micro-/nano-sized phases. Accordingly, low-cost, high strength and ductile Mg-Al-Ca-Zn-Mn alloy sheets with multi-scale multi-phases multi-layer distributed microstructure will be developed. Firstly, the microstructure of the alloy sheet will be tailored by alloy design, adjustment of the heat treatment and reverse temperature field rolling parameters. The evolution and the adjustment rules for the multi-scale multi-phase microstructure will be analyzed to realize the controllable fabrication of the alloy sheets with desired microstructure and mechanical properties. Then, the effect of the multi-scale multi-phase microstructure on the local strain distribution, and their effect on the deformation microstructure and fracture behavior will be analyzed using multi-dimension in-situ characterization methods, to unveil the structure and coupling effects then reveal the strengthening and toughening mechanisms of the Mg-Al-Ca-Zn-Mn alloy sheets. The findings of this project will provide a theoretic guide and experimental basis for the design and fabrication of low-cost, high strength and ductile Mg alloy sheets.