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Vibrational entropy of spinodal decomposition in FeCr

Swan-Wood, T. L. and Delaire, O. and Fultz, B. (2005) Vibrational entropy of spinodal decomposition in FeCr. Physical Review B, 72 (2). Art. No. 024305. ISSN 1098-0121. http://resolver.caltech.edu/CaltechAUTHORS:SWAprb05

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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.


Item Type:Article
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.DEFG02-03ER46055 and BES-MS, W-31-109-ENG-38.
Subject Keywords:iron alloys; chromium alloys; solid solutions; spinodal decomposition; neutron diffraction; stoichiometry; annealing; entropy; Mossbauer effect; free energy; vibrational states; phonons
Record Number:CaltechAUTHORS:SWAprb05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:SWAprb05
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.72.024305
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3277
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:25 May 2006
Last Modified:26 Dec 2012 08:53

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