About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
|
Computational Thermodynamics and Kinetics
|
Presentation Title |
Negative Grüneisen Parameters in Nonmagnetic
bcc-based Intermetallic FeTi at High Pressure |
Author(s) |
Bethuel O. Khamala, Jorge A Munoz |
On-Site Speaker (Planned) |
Bethuel O. Khamala |
Abstract Scope |
FeTi is a brittle intermetallic with the CsCl structure that is stable to 1600K. We investigated its band structure and phonons at different volumes using density functional theory and uncovered a range in which the phonon modes decrease in energy with decreasing volume. This behavior is observed in invar materials, but FeTi is nonmagnetic and there is negligible change in the Fermi surface with pressure. It occurs more generally in materials with negative thermal expansion, but the crystal structure of FeTi is not open and it is stable at high pressure. We show experimental measurements of the phonon density-of-states curves performed via nuclear-resonant inelastic x-ray scattering at pressures up to 55 GPa and x-ray diffraction up to 25 GPa that are consistent with the calculated negative Gruneisen parameters, and an analysis of calculated force constants and band structures that preliminarily point towards orbital hybridization as the origin of the effect. |
Proceedings Inclusion? |
Planned: |
Keywords |
Computational Materials Science & Engineering, High-Temperature Materials, Mechanical Properties |