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Structure, energetics, and mechanical stability of Fe-Cu bcc alloys from first-principles calculations

Liu, Jefferson Z. and van de Walle, A. and Asta, M. (2005) Structure, energetics, and mechanical stability of Fe-Cu bcc alloys from first-principles calculations. Physical Review B, 72 (14). Art. No. 144109. ISSN 1098-0121. http://resolver.caltech.edu/CaltechAUTHORS:LIUprb05

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Abstract

Atomic volumes, magnetic moments, mixing energies, and the elastic properties of bcc Fe1–xCux solid solutions are studied by ab initio calculations based on the cluster expansion framework. For the calculation of concentration-dependent elastic moduli in disordered solid solutions, we introduce a generalization of the cluster expansion technique that is designed to handle tensorial quantities in high-symmetry phases. Calculated mixing energies, atomic volumes, and magnetic moments are found to be in good agreement with available measurements for metastable alloys prepared through nonequilibrium processing techniques. Additionally, the predicted variations of the bulk modulus and shear moduli C44 and C[prime] with respect to copper concentration are calculated for the disordered bcc phase. While the bulk modulus and C44 are positive for all concentrations, C[prime] is predicted to be positive only for Cu concentration less than 50 atomic %, and negative otherwise. Our results thus indicate that the mechanical instability of bcc Cu persists over a wide range of compositions. The implications of the present results are discussed in relation to the observed metastability of bcc Fe-Cu alloys, and the strengthening mechanism of nanoscale bcc precipitates in an alpha-Fe matrix.


Item Type:Article
Additional Information:©2005 The American Physical Society. (Received 8 July 2005; accepted 22 August 2005; published 26 October 2005) This research was supported by the Office of Naval Research Grant No. N00014-03-1-0252/P00002, Dr. Julie A. Christodoulou Program Director. The authors thank Professor M.E. Fine and Dr. D. Isheim at Northwestern for numerous helpful discussions and input.
Subject Keywords:iron alloys; copper alloys; ab initio calculations; magnetic moments; ferromagnetic materials; shear modulus; mechanical stability; mechanical strength; nanostructured materials
Record Number:CaltechAUTHORS:LIUprb05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LIUprb05
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.72.144109
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7346
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:02 Feb 2007
Last Modified:26 Dec 2012 09:31

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