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

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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.