About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
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Symposium
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Deformation and Damage Mechanisms of High Temperature Alloys
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Presentation Title |
Local Phase Transformation Strengthening in Ni-based Superalloys and Induction of Alternative Displacive-diffusional Shearing Pathways |
Author(s) |
Ashton J. Egan, Fei Xue, Gregory Sparks, Timothy Smith, Emmanuelle Marquis, Sammy Tin, Michael Mills |
On-Site Speaker (Planned) |
Ashton J. Egan |
Abstract Scope |
Planar defects and microtwins dominate the intermediate temperature creep regime of Ni-based superalloys, where processes are controlled by diffusion mediated reordering and segregation. Local Phase Transformation (LPT) along defects strengthens alloys possessing critical ratios of η/χ formers. A new LPT strengthening along microtwin boundaries has recently been shown through Electron Channeling Contrast Imaging (ECCI) and Scanning Transmission Electron Microscopy (STEM) studies. This LPT has led to formation of ordered-HCP “nano-laths” via coupled displacive-diffusional mechanism by which strain alternatively accumulates. Advanced characterization of this process was conducted using STEM and atomic resolution Energy Dispersive X-Ray Spectroscopy (EDS), confirming lattice occupancies. Correlative Atom Probe Tomography (APT), as well as STEM modeling, were used for phase confirmation. Orientation effects of operative shearing mechanisms, LPTs, and lath formation were studied in polycrystal specimens and compared to single crystal results. Understanding these processes will inform multiscale modeling efforts and assist in alloy design. |
Proceedings Inclusion? |
Planned: |
Keywords |
Characterization, High-Temperature Materials, Phase Transformations |