Equilibrium atomic compositions of MoxRe1-x(001) and MoxW1-x(001) disordered alloys

A large number of phenomena of great technological importance occur at or near the surface of metals. Thus, a detailed knowledge of the structure and composition of alloy surfaces would have a great impact on a variety of industries. The cluster expansion model for the internal energy in terms of ef...

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Bibliographic Details
Published in:Surface science 2004-03, Vol.553 (1-3), p.30-38
Main Authors: OUANNASSER, S, WILLE, L. T, DREYSSE, H
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Physics
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Summary:A large number of phenomena of great technological importance occur at or near the surface of metals. Thus, a detailed knowledge of the structure and composition of alloy surfaces would have a great impact on a variety of industries. The cluster expansion model for the internal energy in terms of effective cluster interactions is employed to study the thermodynamic properties of two semi-infinite binary alloy systems: MoRe and MoW. A realistic tight-binding Hamiltonian is used with configurational averages computed by the direct method. This framework is applied to calculate the equilibrium atomic compositions of the (001) surface of MoxRe1-x and MoxW1-x systems for different bulk concentrations. In all cases it is found that the Mo component segregates strongly to the surface plane, followed by a Mo depletion in the second plane. The major role played in the segregation process by the relevant quantities, namely, point energies and pair interactions, is emphasized. These results are in good agreement with available experimental data.
ISSN:0039-6028
1879-2758
DOI:10.1016/j.susc.2004.01.055