This DURIP proposal seeks a state-of-the-art ultraviolet picosecond laser-assisted local-electrode atom-probe (LEAP) tomograph for studying the structures of primarily metallic alloys on the sub-nanoscale to nanoscale in predominantly structural materials, with sub-nanoscale spatial resolution and high-mass resolving-power in three-dimensions: the instrument we seek to purchase is the LEAP5000XS, manufactured by Cameca Scientific Instruments, Madison, WI. The LEAP5000 supplants the LEAP4000, which we currently have, with its significantly greater detection efficiency (80% as opposed to 50%). The eight principal investigators contributing to this proposal are all professors in the department of materials science and engineering at Northwestern University and they all have DoD research grants, which will benefit greatly from the use of this latest generation tomograph, the LEAP5000XS. The structural metallic alloys studied are: iron-based, aluminum-based, cobalt-based, nickel-based, magnesium-based, and titanium-based. A common theme for the study of the Fe-, Al-, Co-, Ti- and Mg-based alloys involves the nucleation, growth and coarsening of precipitating phases starting with small clusters of atoms (embryos) as they evolve temporally into nuclei (precipitates) and the relationships of the nanostructures to mechanical properties. The LEAP5000XS has the unique ability to determine the dimensions (sub-nanoscale) and compositions of the clusters (embryos) and nuclei (precipitates) as they evolve temporally, which determines the compositional trajectories, thereby permitting detailed comparisons with the results of codes that are capable of simulating composition trajectories; specifically, TCPrisma and PrecipiCalc. Additionally, understanding atomic scale structure in four-dimensions (3D space plus time) to design and control corrosion resistant nickel-based alloys requires LEAP tomography to understand the atomic mechanisms for corrosion and oxidation. Furthermore, two additional topics will benefit greatly from LEAP tomography: (1) Functionalized two-dimensional nanoelectronic heterostructures, where substitutional defects and surface adsorbates that influence electronic and optical properties are determined; and (2) Bio-inspired assemblies of materials with high fracture toughnesses at low densities provide new avenues for developing defensive and protective materials for military applications.
|Effective start/end date||8/7/17 → 8/14/18|
- Office of Naval Research (N00014-17-1-2870)