Surface segregation of interacting atoms: analytical approach using a thermodynamic model

• Published in: Surface science 2000-01, Vol.445 (2-3), p.526-534
• Main Authors: Gumen, L.N., Feldman, E.P., Yurchenko, V.M., Mel'nik, T.N., Krokhin, A.A.
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Equations of state, phase equilibria, and phase transitions; Equilibrium thermodynamics and statistical mechanics; Exact sciences and technology; Materials science; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solubility, segregation, and mixing; phase separation; Surface segregation; Surface thermodynamics (including phase transitions)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(99)01123-1

Binary atomic interactions are included in the thermodynamic Bragg–Williams model to study the cosegregation of different species of atoms in a multi-component alloy. The kinetics of segregating atoms is described by a set of mutually connected diffusion equations with boundary condition determined by instantaneously equalizing chemical potentials. This model allows analytical solution if t→0 and t→∞. For specific values of parameters our solution shows the approach to equilibrium through a quasi-equilibrium state, that is, the phenomenon of delayed segregation which has been recently analyzed by Jäger in the framework of the quasi-chemical approximation. We also predict a phenomenon of the nonmonotonic segregation.