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Atomic, Electronic, and Magnetic Structure of Iron-Based Sigma-Phases

Published online by Cambridge University Press:  26 February 2011

Pavel A. Korzhavyi ,
Bo Sundman ,
Malin Selleby  and
Börje Johansson
Pavel A. Korzhavyi
Affiliation:
Department of Materials Science and Engineering, Royal Institute of Technology (KTH), SE-100 44 Stockholm, SWEDEN
Bo Sundman
Affiliation:
Department of Materials Science and Engineering, Royal Institute of Technology (KTH), SE-100 44 Stockholm, SWEDEN
Malin Selleby
Affiliation:
Department of Materials Science and Engineering, Royal Institute of Technology (KTH), SE-100 44 Stockholm, SWEDEN
Börje Johansson
Affiliation:
Department of Materials Science and Engineering, Royal Institute of Technology (KTH), SE-100 44 Stockholm, SWEDEN Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-751 21 Uppsala, SWEDEN.
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Abstract

A combination of ab initio total energy calculations with Calphad approach is applied to model the site occupancy and thermodynamic properties of the Fe-Cr, Co-Cr, Fe-V, and Fe-Mo binary sigma-phases as a function of composition and temperature. For each binary sigma-phase the parameters of the model are the ab initio calculated total energies of so-called end-member compounds, which represent all the 25=32 variants of complete occupancy of each of the five crystallographically inequivalent sites by one or the other alloy component. The paramagnetic state of the sigma-phases has been taken into account within the disordered local moment approach. The Fe and Co atoms are found to retain high spin moments when they occupy high-coordination-number sites in the structure. Using our model we were able to reproduce the experimentally observed site occupancy in the FeCr sigma-phase. The calculated site occupancies in the Co-Cr, Fe-V, and Fe-Mo sigma-phases are also presented and discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 842: Symposium S – Integrative and Interdisciplinary Aspects of Intermetallics , 2004 , S4.10
Copyright
Copyright © Materials Research Society 2005

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References

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