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Effect of Pressure on Order and Stability in Alloys: The Case of Al-Ge

Published online by Cambridge University Press:  01 January 1992

P. E. A. Turchi ,
M. Sluiter  and
G. M. Stocks
P. E. A. Turchi
Affiliation:
Lawrence Livermore National Laboratory, Condensed Matter Division (L-268), Livermore, CA 94550
M. Sluiter
Affiliation:
Lawrence Livermore National Laboratory, Condensed Matter Division (L-268), Livermore, CA 94550
G. M. Stocks
Affiliation:
Oak Ridge National Laboratory, Metals and Ceramics Division, Oak Ridge TN 37831-6114
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Abstract

A parameter-free approach to phase stability in substitutional alloys is applied to the influence of pressure on order-disorder phenomena in Al-Ge. The methodology is based upon an application of the Generalized Perturbation Method to the Korringa-Kohn-Rostoker scattering formulation of the Coherent Potential Approximation. For fcc-based Al-Ge alloys, it is shown that the tendency towards phase separation at normal pressure originates from a structural difference between the pure species. By applying pressure, the structural energy difference is reduced, and a significant increase in the tendency towards order, especially for Al-rich alloys, is theoretically observed, leading, as an example, to the possible observation of a DO22 ordered state around 25 at. pct. Ge. The electronic origin of the ordering tendencies induced by pressure is discussed and the theoretical predictions are related to experimental facts.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 291: Symposium O – Materials Theory and Modeling , 1992 , 153
Copyright
Copyright © Materials Research Society 1993

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References

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