About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
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Computational Thermodynamics and Kinetics
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Presentation Title |
Lattice Disorder and Amorphization in Oxygen-containing Immiscible Alloys |
Author(s) |
Qin Pang, Bharat Gwalani, Mathew Olszta, Anqi Yu, Krassimir Bozhilov, Aashish Rohatgi, Suveen N. Mathaudhu, Arun Devaraj, Peter Sushko |
On-Site Speaker (Planned) |
Peter Sushko |
Abstract Scope |
Room temperature solid-phase mechanical intermixing of immiscible metals can give rise to metastable structural motifs and properties that are impossible to realize by solidification of molten metals. Furthermore, these metastable structures can be affected by the presence of gaseous species, such as oxygen, that induce interfacial oxidation-reduction reactions and, thus, modify charge-density distribution.
Here we use simulations based on the density functional theory (DFT) to examine thermodynamic stability of structural motifs contributing to the microstructural hierarchy of Cu-Nb alloys, observed experimentally, and investigate its dependence on the local Cu/Nb concentration ratio and on the concentration of oxygen impurities. We considered several types of structural models, including crystalline random alloys, phase segregated crystalline host-guest systems, and amorphous alloys and established the concentration window of bcc/fcc phase instability and conditions for amorphization accessible under shear deformation. Our ab initio molecular dynamics simulations suggest that charge disproportionation between Cu and Nb strongly favors the formation of NbOx resulting in Nb scavenging oxygen species and contributing to Nb/Cu segregation. |
Proceedings Inclusion? |
Planned: |
Keywords |
Electrometallurgy, Thin Films and Interfaces, Joining |