高强稀土镁合金的高强度和低塑性不匹配问题，限制了其工程应用推广。本项目首次将构型设计引入高强韧Mg-Gd-Y-Zn-Zr合金的开发，通过有效调控合金多模组织中长周期堆垛有序相/γ'相/再结晶晶粒/形变晶粒的层状分布，在晶粒内构建基面γ'相/柱面β'相的网状结构，研发兼具高强度高塑性的稀土镁合金。首先，通过调节热处理、热挤压及时效工艺参数，调控合金多模组织中各组元的分布，研究多模组织演变规律及调控机理，实现合金的可控制备；其次，研究多模组织中各组元对合金局域应变分布的影响规律，及其对合金形变微结构及断裂行为的影响规律，揭示Mg-Gd-Y-Zn-Zr合金的强韧化机制，为高强韧镁合金的构型设计和制备提供理论指导和试验依据。

The mismatching of high strength and low ductility of the high-strength Mg-RE (RE: rare earth) alloys limits their industrial applications. In this project, the configuration design is firstly introduced to develop high-strength and ductile Mg-Gd-Y-Zn-Zr alloys. The layered structure forms by tailoring the multimodal microstructure consisting of long-period stacking ordered (LPSO) phases / γ'phases / dynamically recrystallized (DRXed) grains / hot worked grains, and the network structure forms by controlling the distribution of basal γ' phases / prismatic β' phases inside the Mg grains, so as to develop the Mg-Gd-Y-Zn-Zr alloys with combination of high strength and high ductility. Firstly, the distribution of the constituent of the multimodal microstructure will be tailored by adjusting the processing parameters of heat treatment, hot extrusion and aging treatment. The evolution mechanisms and the adjustment rules for the multimodal microstructure will be analyzed to realize the controllable fabrication of the alloys with desired microstructure. Then, the effect of the distribution of the constituents in the multimodal microstructure on the local strain distribution, and their effect on the deformation microstructure and fracture behavior will be analyzed, to clarify the strengthening and toughening mechanisms of the Mg-Gd-Y-Zn-Zr alloys. The finding of this project will provide a theoretic guide and experimental basis for the configuration design and fabrication of the high strength and ductile Mg alloys.