| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advancing Current and State-of-the-Art Application of Ni- and Co-based Superalloys
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| Presentation Title |
Effect of Stacking Fault Segregation and Local Phase Transformations on Creep Strength in Ni-base Superalloys |
| Author(s) |
Timothy Smith, Brian Good, Tim Gabb, Bryan Esser, Ashton Egan, Laura Evans, David McComb, Michael Mills |
| On-Site Speaker (Planned) |
Timothy Smith |
| Abstract Scope |
In this study, two similar, polycrystalline Ni-based disk superalloys (LSHR and ME3) were creep tested at 760C and 552MPa to approximately 0.3% plastic strain. LSHR consistently displayed superior creep properties at this stress/temperature regime even though the microstructural characteristics between the two alloys were comparable. However, high resolution chemical analysis revealed significant differences between the two alloys among active gamma prime shearing modes. In ME3, Co and Cr segregation and Ni and Al depletion were observed along intrinsic faults - revealing a gamma prime to gamma phase transformation. Conversely in LSHR, W segregation was observed along intrinsic faults. This observation combined with scanning transmission electron microscopy (STEM) simulations confirm an atomic-scale gamma prime-to-D019 χ phase transformation in LSHR. Using experimental observations and density functional theory calculations, a novel local phase transformation strengthening mechanism is proposed that may improve the high temperature creep capabilities of future Ni-base disk alloys. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |