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Published July 1, 2005 | Published
Journal Article Open

Vibrational entropy of spinodal decomposition in FeCr

Abstract

Inelastic neutron-scattering spectra were measured on stoichiometric Fe0.50Cr0.50 prepared as a body-centered-cubic (bcc) solid solution, and after increasing amounts of chemical unmixing on the bcc lattice induced by annealing the solid solution at 773 K. These spectra were reduced by a conventional procedure to a neutron-weighted vibrational density of states. Mössbauer spectrometry was used to characterize the extent of decomposition after annealing. A neutron-weight correction was performed, using results from the Mössbauer spectra and recent data on inelastic nuclear resonant scattering from 57Fe-Cr. The vibrational entropy of decomposition was found to be –0.17±0.01kB/atom, nearly equal to the change in configurational entropy after spinodal decomposition. Effects of vibrational entropy on the thermodynamics of unmixing are analyzed, showing a large effect on the free energy with the formation of Cr-rich zones, and a large effect on the critical temperature for spinodal decomposition for equiatomic Fe0.50Cr0.50.

Additional Information

© 2005 The American Physical Society (Received 2 February 2005; revised 14 June 2005; published 25 July 2005) This work was supported by the U.S. Department of Energy through the Basic Energy Sciences Grant Nos. DE-FG02-03ER46055 and BES-MS, W-31-109-ENG-38.

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August 22, 2023
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