RII Track-4: NSF: Understanding the Nanoscale Incommensurate Modulated Structure in the Titanium Alloys

本基金支持以新型金属设计策略为重点的基础研究，促进材料科学与技术的进步。金属因其在不同载荷条件下的优异性能而被广泛应用于结构材料。然而，在金属中实现高强度和高延展性的协同结合是必要的，也是困难的。本项目旨在研究一种新的策略，通过形成具有良好控制的空间非均质长度尺度的析出相（即非均质析出相结构）来克服钛（Ti）合金的强度-塑性权衡。该项目将利用尖端的透射电子显微镜确定纳米结构在形成Ti合金非均相析出结构中的关键作用。该奖学金将允许PI和一名研究生访问美国首屈一指的电子显微镜中心，麻省理工学院。麻省理工学院的纳米研究设施。该项目将使PI与麻省理工学院建立长期合作关系。这将对内华达大学里诺分校（UNR）的研究能力产生持久的影响。PI将为UNR的学生设计新的电子显微镜和材料科学教育模块，并为里诺社区的K-12学生设计外展活动，以影响年轻一代的学习者，特别是那些传统上代表性不足的群体。茎。这项研究基础设施改善轨道4 EPSCoR研究人员（RII轨道4）项目将为内华达大学里诺分校（UNR）的助理教授和研究生提供奖学金。利用纳米结构是调整钛合金析出相尺寸的有效方法。在本项目中，PI将以纳米尺度不相称调制结构（NIMS）为例，确定Ti合金中与NIMS相关的局部结构、成分和非均相析出结构之间的相关性。本研究的目的是从根本上了解NIMS及其对钛合金热处理过程中组织演变的影响。具体的研究目标有两个：(i)确定钛合金中NIMS的合金成分、加工参数与形成机理之间的关系；（ii）证明了NIMS在钛合金热处理过程中ω和α相析出中的作用。拟议的研究是建立在与世界领先的纳米结构材料科学家和美国首屈一指的麻省理工学院电子显微镜中心的合作基础上的。我们将使用像差校正的Themis Z G3 S/TEM确定NIMS的原子级结构和成分表征，并使用DENS Solution Lightning原位TEM加热支架演示NIMS对钛合金微观组织演变路径的影响。高度先进的原位和原位表征工具的集成对于准确描述钛合金中这些复杂的相变至关重要。本课题的成功完成将有助于进一步了解钛合金纳米结构的微观组织演变，这对于加速发现和开发具有新成分和微观组织的钛合金具有重要意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This grant supports the fundamental research focusing a novel metal designing strategy and promotes the progress of materials science and technology. Metals are widely used structural materials because of their excellent performance under different loading conditions. However, to achieve synergetic combination of high strength and ductility in metals is essential but difficult. This project aims to investigate a new strategy to overcome the strength-ductility tradeoff in titanium (Ti) alloys by forming precipitates with a well-controlled length scale of spatial heterogeneities (i.e., heterogeneous precipitate structure). The project will identify the critical roles of nanostructures in forming the heterogeneous precipitate structure in Ti alloys using the cutting-edge transmission electron microscopy. The fellowship will allow the PI and a graduate student to visit the nation’s premier electron microscopy center, the MIT.nano research facilities at Massachusetts Institute of Technology. The project will enable the PI to establish a long-term collaboration with MIT.nano and new expertise in materials characterization, that will lead to a long-lasting impact on the research capability at University of Nevada, Reno (UNR). The PI will design new electron microscopy and materials science education modules for students at UNR and outreach activities for K-12 students in the Reno community to impact a young generation of learners, especially those from groups traditionally underrepresented in. STEM.This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4) project would provide a fellowship to an Assistant Professor and training for graduate student at the University of Nevada Reno (UNR). Utilizing nanostructures is an effective method to tune the size of precipitates in Ti alloys. In this project, the PI will use nanoscale incommensurate modulated structure (NIMS) as an example to identify the correlations between the local structure, composition and heterogeneous precipitate structure related to NIMS in Ti alloys. The goal of this research is to fundamentally understand the NIMS and its influence on the microstructure evolution during thermal treatment in the Ti alloys. Two specific research aims will be pursued: (i) Identifying the relationship between the alloy composition, processing parameter and the formation mechanism of the NIMS in Ti alloys; and (ii) Demonstrating the role of NIMS in ω and α phase precipitation during heat treatment in Ti alloys. The proposed research is built on the collaboration with the world-leading nanostructured materials scientist and the nation’s premier electron microscopy center at Massachusetts Institute of Technology. We will identify the atomic-level structure and composition characterization of NIMS using the aberration-corrected Themis Z G3 S/TEM and demonstrate the influence of NIMS on microstructure evolution pathways in Ti alloys using the DENS Solution Lightning in-situ TEM heating holder. The integration of highly advanced ex- and in-situ characterization tools is essential for an accurate description of these complex phase transformations in Ti alloys. The successful completion of the proposed project will advance the fundamental understanding of the microstructure evolution related to the nanostructures in Ti alloys, that is critical for accelerating the discovery and development of Ti alloys with a new composition and microstructure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.