|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Thermal and Mechanical Stability of Nanocrystalline Materials
||Effects of Nanotwinning and Nanocrystallinity on the Precipitation Behavior of a Ni-Mo-Cr Superalloy
||Megan Emigh, Jessica Krogstad
|On-Site Speaker (Planned)
Superalloys are a candidate material for future microelectromechanical systems in extreme environments due to their oxidation resistance and toughness at high temperatures. In this study, a Ni-25Mo-8Cr superalloy film was formed by quenching it from the vapor phase via direct current magnetron sputtering onto a water-cooled substrate. This resulted in a nanograined, columnar microstructure with nanotwinning perpendicular to the growth direction. A standard aging heat treatment on the delaminated film produced γ-Ni<sub>3</sub>Mo precipitates rather than typical Ni<sub>2</sub>(Mo,Cr) precipitates. Phase identification was carried out via transmission electron microscopy with diffraction. In a separate heat treatment, a section of film was exposed to a solution anneal and quench prior to aging. This treatment eliminated the nanotwinning but preserved a sub-micron grain structure. Subsequent aging precipitated the Ni<sub>2</sub>(Mo,Cr) phase. These results underscore the importance of careful microstructure control of superalloys as we push their limits in future small-scale applications.
||Planned: Supplemental Proceedings volume