About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
|
| Symposium
|
Computational Thermodynamics and Kinetics
|
| Presentation Title |
The formation entropy and free energy of dislocations |
| Author(s) |
Aaron Kohnert, Laurent Capolungo |
| On-Site Speaker (Planned) |
Aaron Kohnert |
| Abstract Scope |
Entropy in solids, both vibration and configurational, is essential to understanding phase stability and deformation kinetics. In computational mechanics, the entropy associated with dislocations is frequently invoked as important to thermally activated plastic flow but only formation energies for dislocations have been quantified explicitly. We derive the intrinsic formation entropy of dislocation lines. It arises from anharmonicity, generating long-range changes in the vibrational entropy of the lattice under the elastic fields of dislocations. This entropy is large in magnitude, and will overwhelm other contributions such as from network configuration or oscillations under the line tension. Using the measured elastic constants of the pure elements, the resultant free energy of formation for dislocations monotonically decreases in most metals, and always falls negative past a finite critical temperature. This occurs when the free energy change associated with elastic shear in the crystal becomes negative, and closely aligns with a phase transformation temperature. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Mechanical Properties, Phase Transformations, Computational Materials Science & Engineering |