| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
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| Symposium
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Microstructural Template Consisting of a Face-Centered Cubic Matrix with Ordered Precipitates: Microstructural Evolution and Properties
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| Presentation Title |
In-situ Transmission Electron Microscopy Investigation of Continuous Precipitation of Ni3Mo in a Ni-25Mo-8Cr Alloy Formed by Direct Current Magnetron Sputtering |
| Author(s) |
Megan G. Emigh, Jessica A. Krogstad |
| On-Site Speaker (Planned) |
Jessica A. Krogstad |
| Abstract Scope |
The microstructure of Ni-25Mo-8Cr superalloy thin films prepared via direct current magnetron sputtering (DCMS) is shown to be key to manipulating and understanding phase transformations. Specifically, the columnar, highly textured, and nanotwinned grains are shown to facilitate precipitation of the equilibrium DOa (Ni3Mo) phase during a mild heat treatment. In situ observation in diffraction mode confirms that precipitation behavior in these defect-dense thin films is not merely kinetically accelerated; instead, the pathway is fundamentally altered. Short-range ordering (SRO) behavior was observed upon reaching 650ºC. SRO has been documented as part of the FCC-precipitation pathway, but has not previously been reported for HCP-based precipitates. Conversely, elimination of the nanotwins leads to precipitation of metastable Ni2(Mo,Cr) precipitates. The straightforward capacity to select one of several possible phase transformation pathways presents an opportunity to create precisely tuned microstructures, while simultaneously providing unprecedented insight on these complex phase transformations. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |