About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
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Symposium
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Advances in Multi-Principal Element Alloys III: Mechanical Behavior
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Presentation Title |
Ab Initio Study of Screw Dislocation Core Structure and Energy Landscape in bcc 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 perform ab initio computational studies of the core structure and energy landscape of screw dislocations in bcc Nb-Ta-Ti-Hf high-entropy alloys (HEAs). We focus on two HEA compositions: equiatomic Nb0.25Ta0.25T0.25Hf0.25, and Nb-rich Nb0.45Ta0.25Ti0.15Hf0.15. Relaxations of the dislocation core in its ground state configuration show that the core structure strongly depends on composition. Specifically, whereas the Nb-rich alloy features an almost ideally symmetric core, the equiatomic composition shows a core structure featuring pronounced asymmetry. Further, we calculate the energy landscape seen by the dislocation as a function of its position in the (111) plane, examining high-symmetry configurations. We show that energy fluctuations associated with these different core positions are as relevant as those driven by chemical disorder. Finally, we present results showing that screw dislocations feature departures from the Schmid law, both twinning/antitwinning asymmetry and non-glide effects. |
Proceedings Inclusion? |
Planned: |
Keywords |
High-Entropy Alloys, Computational Materials Science & Engineering, |