高强钛合金非均质层状多级组织塑性变形模式的调控与强韧化机理

最近研究结果发现多尺度层级组织结构的合金兼顾强度与塑性匹配，有望克服工程合金普遍存在的强度-塑性此消彼长的规律。本项目采用粉末冶金技术制备高强钛合金，通过冷热加工构建了特殊的非均质层状多级组织结构，通过间隙原子氧来调控塑性变形模式，获得高强度、高塑性、高韧性的良好性能匹配（如Rm=1700MPa、A5=7.5%、Kq=57.6MPa∙m1/2）。拟采用微米-纳米-原子尺度的组织结构表征技术，分析非均质层状多级组织演变规律和结构特点，并结合力学性能的原位测试等手段，阐明高氧含量高强钛合金的滑移变形方式及规律，揭示多尺度层级组织界面在塑性变形协调中的作用机理，揭示合金强度-塑性-韧性良好匹配的微观机制。进一步阐明高强钛合金中的非均质层状多级组织形成与控制关键因素，以及塑性变形过程中间隙元素氧对合金良好力学性能匹配的作用机理，开拓通过组织结构与塑性变形模式协同作用提高钛合金综合力学性能的新思路。

It is recently found that alloys with multiscale and multi-hierarchical structure can maintain high-plasticity with high-strength, which is expected to become a solution for the ubiquitous strength-ductility tread-off of engineering metallic materials. Recently, the applicant of the current project applied powder metallurgy technique to prepare high strength titanium alloy with high oxygen level. Construction of heterogeneously-laminated/multi-hierarchical precipitation structure and deformation manipulation of the alloy are achieved by designing cold/hot processing and interstitial atom addition. Then, excellent strength-ductility-toughness synergies (e.g. Rm=1700MPa, A5=7.5%, Kq=57.6MPa∙m1/2) are realized in the high-strength titanium alloy. The current project is aiming to analyze the evolution process and features of the resultant microstructure by scale-span material characterization techniques, to reveal the alloy’s sliding mode and interfacial effects of the special microstructure during plastic deformation by in-situ observations of mechanical testing, and to clarify the coordination mechanism of outstanding strength-ductility-toughness matching. Based on these, the research will focus on the origination/controlling mechanism of the special microstructure, and reveal the mechanism of high interstitial oxygen level for achieving superior synergy of mechanical properties of the alloy. The outcomes of the project can not only make a significant contribution in inaugurating new strategies for enhancing the overall performance of titanium alloys by synergistic effect of microstructure and plastic deformation manipulation, but also provide vital supports for the development of strengthening/toughening theory for metallic materials.