About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
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Computational Thermodynamics and Kinetics
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Presentation Title |
A First-principles Analysis of the Temperature Dependence of Stacking Fault Energies in Mg and Ti |
Author(s) |
Julian L. Brodie, Maryam Ghazisaeidi |
On-Site Speaker (Planned) |
Julian L. Brodie |
Abstract Scope |
Magnesium, titanium and their alloys are interesting for their high strength-to-weight ratio and application as structural metals in automotive and aerospace industries. However, these hexagonal-close-packed (hcp) metals suffer from an anisotropic plastic response resulting in insufficient slip systems available at low temperatures. As five independent slip systems are required for high ductility in polycrystalline metals, according to the von Mises criterion, activation of 〈c+a〉 dislocations are crucial in improving room temperature formability.
We use density functional theory (DFT) and phonon analysis to determine the stability of dislocations in Mg and Ti at low temperatures. DFT is used to compute the stacking fault energy on relevant slip planes. Density Functional Perturbation Theory coupled with phonon analysis is used to determine how the free energy of stacking faults changes with temperature. Additionally, the BCC phases of Mg and Ti are studied for their potential role in the instability of certain 〈c+a〉 dislocations. |
Proceedings Inclusion? |
Planned: |