About this Abstract |
Meeting |
MS&T21: Materials Science & Technology
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Symposium
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High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond II
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Presentation Title |
The Formation of Complex Ternary Oxides in Refractory Complex Concentrated Alloys |
Author(s) |
Logan G. Ware, Brahim Akdim, Christopher Woodward, Tinuade Daboiku, Todd Butler, Oleg Senkov, Samuel Kuhr, Noah Philips, Michael S. Titus |
On-Site Speaker (Planned) |
Logan G. Ware |
Abstract Scope |
Refractory complex concentrated alloys (RCCAs) are a class of alloys that exhibit high strength, even at temperatures higher than those achievable using conventional superalloys. A subset of these alloys exhibits improved oxidation resistance associated with the formation of complex ternary oxides that form protective layers, much like alumina or chromia. One such alloy system is Hf-Ta with alloying additions of Mo, Nb, and W. These alloys exhibit high strength and ductility, and their oxidation resistance is due to the oxide Hf6Ta2O17. This oxide has been shown to prevent oxygen ingress, but its exact structure and the effect of alloying elements on oxygen diffusion through the lattice are unknown. This presentation will detail the statistical thermodynamics of the Hf6Ta2O17 superstructure, both at 0 K and elevated temperature. The atomic configuration of the oxide, both with and without alloying elements, and its effect on oxygen vacancy formation energy will be discussed. |