|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Hume-Rothery Award Symposium: Thermodynamics of Materials
||Reduced Elastic Anisotropy of Cementite at Moderate Temperatures from Nonharmonic Effects
||Jane Herriman, Lisa Mauger, Olle Hellman, Sally June Tracy, Matt Lucas, Jorge Munoz, John Horwath, Jackie Li, Brent Fultz
|On-Site Speaker (Planned)
When measuring the vibrational spectra of cementite, Fe3C, with better accuracy than previously possible, we observed an unexpected stiffening of low-energy phonon branches with increasing temperature in the ferromagnetic phase. In follow-up computations, we found that the quasiharmonic approximation – the conventional model – fails to reproduce this unexpected stiffening, but constant volume calculations including finite temperature phonon-phonon interactions reproduce this effect. These results suggest that nonharmonic effects significantly impact the behavior of cementite at moderate temperatures, which may have important implications for the elastic properties of cementite: Previous computational studies suggested high elastic anisotropy on the basis of 0K calculations; this suggestion is at odds with published experimental work. The presence of nonharmonic effects at moderate temperatures potentially explains this discrepancy as the observed stiffening drives a reduction in the elastic anisotropy of cementite above 0K.
||Planned: A print-only volume