|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Hume-Rothery Award Symposium: Thermodynamics of Materials
||Phonon Dynamics and Vibrational Entropy of bcc Fe at Elevated Temperatures
||Lisa Mauger, Matthew S Lucas, Jorge A Munoz, Sally June Tracy, Brent Fultz
|On-Site Speaker (Planned)
The phonon density of states (DOS) of bcc Fe was measured from low temperatures up through the 1185K fcc phase transition using Nuclear Resonant Inelastic X-ray Scattering. At higher temperatures all phonons shift to lower energies (soften) with thermal expansion. However, the low energy transverse phonon modes soften more rapidly, showing strongly nonharmonic behavior before the magnetic Curie transition. The vibrational entropy was calculated from the DOS curves and its contribution to the high temperature thermodynamics of bcc Fe is discussed. A lattice dynamics model was optimized to fit the measured phonon DOS spectra, providing interatomic force constants and phonon dispersion information. The unusually large nonharmonic phonon behavior of bcc Fe at elevated temperatures is attributed to magnon-phonon interactions, which is discussed in terms of the temperature dependences of the interatomic force constants.
||Planned: A print-only volume