稀土镁合金多级梯度结构的调控与强韧化机理

高性能稀土镁合金的强度和塑性不匹配问题严重限制了其应用潜力。本项目巧妙利用稀土元素在镁合金界面偏聚和析出的特点，构筑晶粒梯度、孪晶梯度和第二相梯度共存的多级梯度结构，充分发挥多级梯度结构单元之间的协调变形能力，实现稀土镁合金强度和塑性的优化匹配。首先，研究表面机械研磨处理和热处理对稀土镁合金多级梯度结构的影响规律，揭示稀土镁合金多级梯度结构的形成机制；其次，研究稀土镁合金多级梯度结构的塑性变形行为，重点关注多级梯度结构单元协调变形的组织演变规律，揭示稀土镁合金多级梯度结构的协调变形机制；最后，研究稀土镁合金多级梯度结构界面的力学行为和断裂机制，揭示稀土镁合金多级梯度结构的强韧化机制。本研究将为高性能稀土镁合金结构调控与强韧化提供一种新思路，进一步完善稀土镁合金的制备加工理论，有力拓展稀土镁合金的应用范围

The mismatch of strength and plasticity of Mg-Re alloy severely limits its application potential. This research uses the characteristics of segregation and precipitation of rare earth elements at the interface of Mg alloys to construct a hierarchical gradient structure in which the grain gradient, twin gradient and second-phase gradient coexist, and give full play to the coordinated deformation ability of the hierarchical gradient structural units to achieve optimal matching of strength and plasticity of Mg-Re alloys. First, study the influence of surface mechanical grinding treatment and heat treatment on the hierarchical gradient structure in Mg-Re alloy, and reveal the formation mechanism of hierarchical gradient structure of Mg-Re alloy; second, study the plastic deformation behavior of hierarchical gradient structure of Mg-Re alloy, focusing on the evolutionary structure of the coordinated deformation of the hierarchical gradient structure unit reveals the coordinated deformation mechanism of the hierarchical gradient structure of Mg-Re alloy Strong and tough mechanism. This research will provide a new idea for the structural control and strengthening and toughening of high-performance Mg-Re alloys, further improve the preparation and processing theory of Mg-Re alloys, and effectively expand the scope of application of rare earth magnesium alloys.