基于畸变能调控LPSO相的界面迁移行为及其对镁合金强度和塑性的影响机制研究

This project takes aims at the contradictory of the strength and ductility in magnesium alloys. And it focuses on the researches about the new phenomenon which both the strength and plasticity could be enhanced during the aging behavior. Based on it, Mg-RE-Zn alloys which contains LPSO phase will be taken as the research objects and the energy will be considered. The relationship of “Component/Processing – Distortion Energy – Interface Migration Behavior – Microstructure – Deformation Behavior – Mechanical property” will be discussed by a new angle of the interface migration behavior. In this program, according to changing and introducing the distortion energy, such as stacking fault energy and crystal face energy, in specific crystal face by alloying and strain introducing, the interface migration behavior, including nucleation and growth, can be regulated. Then the structure and morphology of LPSO phase will be controlled, and the deformation behavior will be affected. Combined with the first-principle calculation and in situ method in TEM technology, we could develop the mechanism of strengthening and toughness in LPSO phase magnesium alloys. Finally, this project could supply some guidance for research and development of the high strength and high ductility magnesium alloys.

针对目前高强镁合金强度塑性不易兼得的难题，申请人基于前期实验发现“含LPSO相镁合金在时效过程中强度塑性同时增加”的新现象，以Mg-RE-Zn合金为研究对象，通过引入能量观念，从界面迁移的角度入手重点研究含LPSO相镁合金“成分/工艺-畸变能-界面迁移-结构形态-变形行为-力学性能”之间的联系。项目通过合金元素和应变诱导等调控手段向特定晶面引入或改变畸变能（重点考虑层错能和晶面能），合理调控LPSO相的形核和生长等界面迁移行为，以此调控LPSO相的结构形态并影响其变形行为，结合第一性原理计算和先进电子显微学技术（原位TEM等），最终揭示LPSO相对镁合金强度和塑性的影响机制，为研发新型高强高韧镁合金提供理论指导。

轻质高强韧镁合金是航空航天、国防军工及现代工业发展中紧迫的轻量化材料需求之一，对缓解我国资源短缺、能源危机和环境污染的意义重大。含长周期堆垛有序相（LPSO 相）的Mg-RE-TM 是目前性能最好的高强镁合金体系，其强度在500MPa以上，已基本达到商用高强铝合金的强度，但延伸率却普遍偏低（通常在5%以下），无法满足作为关键承力构件的工程应用。如何利用有效的强韧化途径，解决高强镁合金强度塑性不可兼得的矛盾，已成为一个亟待解决的科学难题。本项目以含 LPSO 相的 Mg-RE-Zn 系镁合金作为研究对象，从调控畸变能的角度入手，通过合金元素控制和应变诱导等手段向合金中引入或改变畸变能，研究了不同元素对LPSO相种类、形貌、数量的作用规律，揭示了LPSO相的界面迁移规律；研究了不同热处理工艺和塑性成形工艺下合金中LPSO相的形貌演化规律，获取应变诱导作用下， LPSO相界面迁移行为和形态演化规律之间的联系。最终揭示 LPSO 相对合金强度和塑性的影响机制，为研发新型高强高韧镁合金提供理论指导。