自生微/纳米颗粒相协同强化钛基复合材料的超塑性变形机制研究

High strength and ductility/toughness well-matched in-situ particulate reinforced titanium matrix composites used in aeronautic and astronautic are one of a major international research interest. The key scientific problems are mainly reflected in two aspect: hard controlling of reinforcements and deformation processing, which is also the focus point of the component forming with the lightweight and a complex structure. Superplastic forming is one of the important method to solve the deforming problem in complex large components. This project attempt to propose superplastic forming technology for the micro/nano particles synergistic reinforced titanium matrix composites, making up the limitation in hard deformation of same scaled-single and hybrid reinforced titanium matrix composites. We comprehensively applied the superplastic processing theory, experimental method and virtual reality simulation to study the deformation behavior and mechanism of micro/nano particles reinforced titanium matrix composite, proposing quantitative analysis to revel the microstructural evolution in macro and micro scale. Further studying the influence of superplastic forming on the reinforcements and microstructure in multi-scale coupling deformation and heat transfer. Finally, the controlling theory and technology could be developed for superplastic forming of large billet. It has a strategic significance to satisfy the need of large superplastic forming technology for high-performance titanium matrix composites in aerospace and aviation field.

高强度－塑/韧性匹配良好的航空航天用自生颗粒增强钛基复合材料的制备与加工一直是国际学术前沿方向之一。其关键科学难题主要体现在两个方面：增强体控制难和变形加工难，也是该材料轻量化复杂整体构件成形关注的焦点内容，而超塑性变形加工是解决该材料复杂大件成形制造能力不足的重要途径之一。本项目拟提出自生微纳米颗粒协同增强钛基复合材料的超塑性变形加工技术，弥补同尺度一元或多元增强钛基复合材料难加工的局限性；综合采用超塑性加工理论、实验和有限元拟实方法，深入研究微/纳双尺度颗粒增强钛基复合材料微观塑性变形行为与机理，提出从宏观到微观尺度定量化分析高温加载过程中微观组织演变机制，揭示在变形－传热－多尺度耦合下，超塑性变形加工对增强体和微观组织的作用与调控机制，从而发展钛基复合材料大件超塑成形全过程的控制理论技术，对解决航空、航天新技术发展对高性能钛基复合材料大件超塑性成形技术的重大需求具有重要的战略意义。

面向航空航天用的高强、高模钛基复合材料复杂构件超塑性一体化成形，针对超塑性变形作用下微/纳协同强化钛基复合材料界面演化过程复杂、组织结构难以调控的技术问题，本项目综合采用塑性加工理论、实验和计算机仿真方法，研究建立了超塑性变形条件下宏观热力学参数及其演变历史对复合材料显微组织演变的协调影响机制，以及多尺度颗粒协同增强钛基复合材料的超塑性热变形行为，建立了通过变形—传热—尺度耦合分析来探索和确定多尺度颗粒增强钛基复合材料高温超塑性变形工艺和组织的协调机制，揭示了复合材料形变、微观特性与性能的相关规律。从多尺度上对增强体形貌特征进行定量化调控，深入揭示了多尺度颗粒增强复合材料微观塑性变形行为与机理，阐明了多尺度颗粒与基体协调变形行为与机制，揭示了高温超塑性变形后增强体尺度演变规律，通过变形—传热—尺度耦合分析确定了多尺度颗粒增强复合材料超塑性变形工艺和组织的协调机制，建立了包含应变、应变速率和温度等参数的超塑性“变形安全判据”，突破了钛基复合材料超塑成形的关键技术，开发出钛基复的超塑性成形构件，掌握颗粒增强钛基复合材料超塑性变形后力学性能和材料失效模式，进一步拓展超塑性成形工艺应用的材料领域范围，成功制备出高性能钛基复合材料坯锭并制定了相应的工艺规范，解决颗粒增强钛基复合材料精密锻件近净超塑成形组织与性能控制难的问题。最终采用超塑成形技术实现了小尺寸复杂舵叉构件的一次精密成形，并通过后处理工艺实现了对其组织性能的调控，完成了对典型舵叉构件的研制。