|About this Abstract
||2010 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||Effects of Tempering on Fe-Atom Vibrations in Martensitic Steel
||Lisa Mauger, Brent Fultz
|On-Site Speaker (Planned)
Martensitic steels have non-equilibrium distributions of carbon atoms, and the rearrangements of carbon atoms upon tempering are responsible for major changes in mechanical properties. We studied how the phonon dynamics and vibrational entropy of AISI 1095 steel and quenched Fe-C alloys are changed by tempering. Measurements with inelastic nuclear resonant scattering of synchrotron radiation showed that the quenched martensite had a broadened phonon spectrum that sharpened with tempering towards that of pure bcc Fe. Large changes to the phonon spectra occurred after tempering at only 125 C. The vibrational entropy of the quenched material was approximately 0.1 k_B/atom larger than that of the tempered alloys, although the vibrational spectra of carbon atoms remains to be obtained. The implications to the thermodynamic stability of martensite seem to be modest.
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