Defects and the functionality of metallic structural thin films
Structure-property-processing relationships are at the heart of traditional materials science and engineering. In the field of metallurgy, careful refinement of these parameters over many decades have lead to many high performance alloys that can operate at high homologous temperatures, under severe corrosive conditions and extreme mechanical loads. As the scale of these structural alloys shrinks for applications including microelectromechanical systems (MEMS) and protective coatings, we are working to expand our understanding of fundamental relationships between the nonequilibrium microstructures, which are typical of films/structures at this scale, and the evolution of film properties. This work involves thin film processing, shaping and characterization using sputtering methods, current assisted densification schemes, electron microscopy and particularly small-scale mechanical characterization techniques.
Relevant publications:
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M.G. Emigh, J.A. Krogstad. “In situ transmission electron microscopy investigation of continuous precipitation of HCP-based Ni3Mo in a superalloy formed by direct current magnetron sputtering.” Scripta Mater. 173, 66-69 (2019). DOI: 10.1016/j.scriptamat.2019.07.028
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P. Shetty, M. Emigh, J.A. Krogstad. “Coupled oxidation resistance and thermal stability in sputter deposited nanograined alloys.” J Mater Res. 34 [1], 48-57 (2019) DOI: 10.1557/jmr.2018.403.
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M. Emigh, R. McAuliffe, T. Weihs, K.J. Hemker, D.P. Shoemaker, J.A. Krogstad. “Influence of a nanotwinned, nanocrystalline microstructure on aging of a Ni-25Mo-8Cr superalloy.” Acta Mater. 156, 411-419 (2018). DOI: 10.1016/j.actamat.2018.07.007
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Gi-Dong Sim; J.A. Krogstad; K.Y. Xie; S. Dasgupta; G.M. Valentino; T.P Weihs, K.J. Hemker. “Tailoring the mechanical properties of sputter deposited nano-twinned Nickel-Molybdenum-Tungsten films.”Acta Mater. 144 216-225 (2018). DOI: 10.1016/j.actamat.2017.10.065.
- Sim, G. D., Krogstad, J. A., Reddy, K. M., Xie, K. Y., Valentino, G. M., Weihs, T. P., & Hemker, K. J. (2017). Nanotwinned metal MEMS films with unprecedented strength and stability. Science Advances, 3(6), e1700685. DOI: 10.1126/sciadv.1700685.