高性能Mg-Gd-Zn(-Zr)镁合金中LPSO结构形成和演化的原位动态观察、组织调控机制和强韧化机制研究

At presnt, long period stacking ordered (LPSO) structures could be formed only in the Mg-RE-Zn/Cu/Ni/Al series alloys.In this project, Mg-Gd-Zn(-Zr) series alloys will be selected as studied alloys. By theories and experiment studies, in situ observation of crystal growth process,especilally about LPSO structure in the Mg alloy will be carried out, by synchrotron microradiography and small-angle X-ray scattering and confocal laser scanning microscopy(CLSM) and high temperature metallography.It could be clarified that the formation conditions and mechanisms, evolution regularity of LPSO structure (and stacking order).The microstructures, including grain sizes, LPSO structure(and stacking order) within matrix, X phase with LPSO structure distributed in grain boundaries, characteristics of grain boundarie and secondary particles, can be controlled, through systematically studying of the effect of alloy compositions, solidification and heat treatment parameters on the microstructure and mechanical properties in the alloys.The most two important questions will be focused on studying of the formation and evouation of LPSO structure(and stacking order) within matrix, X phase with LPSO structure distributed in grain boundaries. At last, effective microstructural controlling technologies and mechanisms and strengthening-toughening mechanisms of LPSO structure(and stacking order) can be obtained， which will act as theoretical and experimental guidance in the development and application of magnesium alloys with ultra-high strength and high toughening.

Mg-RE-Zn/Cu/Ni/Al合金系是目前唯一存在长周期有序(LPSO)结构的镁合金体系。本项目选择Mg-Gd-Zn(-Zr)系合金为研究对象，通过理论研究和试验研究，采用同步辐射X射线成像技术和小角度X射线散射方法结合共焦激光扫描显微镜和高温金相显微镜等先进材料分析手段来原位观察镁合金晶体生长(重点是LPSO结构)的动态过程,从而探索和研究出LPSO结构（和层错）的形成条件、形成机制、演化规律。采用优化合金成分和改变铸造工艺、热处理工艺来调控合金的组织，主要包括晶粒尺寸以及晶内LPSO结构（和层错）、晶界X相（具有LPSO结构）、晶界特性和第二相粒子尺寸、分布、形态等的演化情况以及对力学性能的影响，重点研究工艺参数对晶界X相和晶内LPSO结构（和层错）的形成与演化这两大基本问题。最终，获得有效的组织调控手段和机制并探索出强韧化机制，为超高强高韧镁合金的开发与应用提供理论和实验指导。

Mg-RE-Zn/Cu/Ni/Al合金系是目前唯一存在长周期有序(LPSO)结构的镁合金体系。本项目选择Mg-Gd-Zn(-Zr)系合金为研究对象，通过理论研究和试验研究，采用同步辐射X射线成像技术和小角度X射线散射方法结合共焦激光扫描显微镜和高温金相显微镜等先进材料分析手段来原位观察镁合金晶体生长(重点是LPSO结构)的动态过程,从而探索和研究出LPSO结构（和层错）的形成条件、形成机制、演化规律。采用优化合金成分和改变铸造工艺、热处理工艺来调控合金的组织，主要包括晶粒尺寸以及晶内LPSO结构（和层错）、晶界X相（具有LPSO结构）、晶界特性和第二相粒子尺寸、分布、形态等的演化情况以及对力学性能的影响，重点研究工艺参数对晶界X相和晶内LPSO结构（和层错）的形成与演化这两大基本问题。最终，获得有效的组织调控手段和机制并探索出强韧化机制，为超高强高韧镁合金的开发与应用提供理论和实验指导。