About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
|
Symposium
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Computational Thermodynamics and Kinetics
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Presentation Title |
Local Lattice Distortions and Structural Phase Stability in Nb-Ta-Ti-Hf High-entropy Alloys |
Author(s) |
Pedro Borges, Robert O Ritchie, Mark Asta |
On-Site Speaker (Planned) |
Pedro Borges |
Abstract Scope |
We report ab initio computational results for the structure and energetics of high-entropy alloys with composition NbxTa0.25Ti(0.75-x)/2Hf(0.75-x)/2. The intrinsic competition between bcc, hcp and omega phases, as a function of the composition x, are investigated highlighting the important role of the ratio of group IV (Ti and Hf) versus group V (Nb and Ta) elements, and local lattice distortions (LLD) in stabilizing the bcc crystal. The energetic stability of the bcc phase increases with increasing x, with the energy difference between omega and bcc decreasing as the concentration of Ti and Hf increases. Detailed analyses of phonons and LLD in the bcc phase show evidence of correlated LLD at lower values of x, reflecting local structural distortions toward the omega phase, but not hcp. The degree of omega-collapse is however partial due to the presence of Ta and Nb holding back the transformation of the bcc lattice. |
Proceedings Inclusion? |
Planned: |
Keywords |
High-Entropy Alloys, Computational Materials Science & Engineering, Other |