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Ordering Energy of B2 Alloys Calculated in the Frozen Potential and Harris Approximations

Published online by Cambridge University Press:  28 February 2011

W. A. Shelton ,
D. M. Nicholson ,
G. M. Stocks ,
F. J. Pinski ,
D. D. Johnson ,
P. Sterne  and
W. M. Temmerman
W. A. Shelton
Affiliation:
Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6114
D. M. Nicholson
Affiliation:
Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6114
G. M. Stocks
Affiliation:
Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6114
F. J. Pinski
Affiliation:
University of Cincinnati, P.O. Box 2008, Oak Ridge, TN 37831-6114
D. D. Johnson
Affiliation:
Sandia National Laboratories, P.O. Box 2008, Oak Ridge, TN 37831-6114
P. Sterne
Affiliation:
Lawrence Livermore Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6114
W. M. Temmerman
Affiliation:
SERC Daresbury Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6114
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Abstract

It has been established that the coherent potential approximation can successfully describe the energy of random alloys [1]. It has also served as the basis of generalized perturbation method [2] and concentration wave [3] xscalculations of the energy of short range ordered alloys. The multisublattice coherent potential, (MCPA) is the natural extension of the CPA with which to address long range order (LRO). Using the recently developed multisublattice coherent potential approximation Korringa Kohn Rostoker [4], (MCPA-KKR) code the elgenvalue sum can be calculated as a function of LRO. This allows the evaluation of the ordering energy by either of two approximations. The frozen potential approximation (FPA) [5] assumes that the muffintin single site potentials do not change as the long range order is varied; the Harris Approximation, (HA) [6], as applied in this work, assumes that the single site charge densities do not change as the long range order is changed. These two methods of calculating the ordering energy will be compared with each other and to experiment for several systems including CuZn, NiAl, and NiAl with zinc additions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 186: Symposium I – Alloy Phase Stability and Design , 1990 , 113
Copyright
Copyright © Materials Research Society 1991

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References

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