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The Free Energy Simulation Approach to Grain Boundary Segregation In Cu-Ni

Published online by Cambridge University Press:  26 February 2011

H. Y. Wang ,
R. Najafabadi ,
D. J. Srolovitz  and
R. Lesar
H. Y. Wang
Affiliation:
University of Michigan, Dept. of Materials Science and Engineering, Ann Arbor, MI 48109
R. Najafabadi
Affiliation:
University of Michigan, Dept. of Materials Science and Engineering, Ann Arbor, MI 48109
D. J. Srolovitz
Affiliation:
University of Michigan, Dept. of Materials Science and Engineering, Ann Arbor, MI 48109
R. Lesar
Affiliation:
Los Alamos National Laboratory, Theoretical Division, Los Alamos, NM 87545
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Abstract

A new, accurate method for determining equilibrium segregation to defects in solids is employed to examine the segregation of Cu to grain boundaries in Cu-Ni alloys. The results are in very good agreement with the ones given by Monte Carlo. This method is based upon a point approximation for the configurational entropy, an Einstein model for vibrational contributions to the free energy. To achieve the equilibrium state of a defect in an alloy the free energy is minimized with respect to atomic coordinates and composition of each site at constant chemical potential. One of the main advantages this new method enjoys over other methods such as Monte Carlo, is the efficiency with which the atomic structure of a defect, segregation and thermodynamic properties can be determined. The grain boundary free energy can either increase or decrease with increasing temperature due to the competition between energetic and configurational entropy terms. In general, the grain boundary free energy increases with temperature when the segregation is strongest.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 209: Symposium K – Defects in Materials , 1990 , 219
Copyright
Copyright © Materials Research Society 1991

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References

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