On some Spectacular Surface Segregation Behaviors in CuNi and PtNi Alloys Analyzed within the Tight-Binding Ising Model
In an alloy, the concentration near the surface can be different from the one in the bulk. This is the so-called surface segregation phenomenon , which is usually modelled on the basis of a description of the total energy as a sum of pair interactions. Unfortunately, it is well known that the cohesive energy of transition metals and alloys does not reduce to such a sum . We will show here than, when interested in surface segregation processes, one can derive from the electronic structure of the disordered alloy an effective Ising hamiltonian containing a linear term (which proves to be very close to the difference in surface tensions between the constituents) and a quadratic one (which involves effective pair interactions). This is the recently developed Tight-Binding Ising Model (TBIM) .
KeywordsCohesive Energy Surface Segregation Band Filling Layer Sandwich Effective Pair Interaction
Unable to display preview. Download preview PDF.
- 2.J. Friedel, “The Physics of Metals”, J.M. Ziman ed., (Cambridge University Press) 340, 1969.Google Scholar
- 5.F. Ducastelle, “Advanced Study Institute on Alloy Phase Stability”, Maleme (Grèce), 1987.Google Scholar
- 10.B. Legrand and G. Tréglia, “The Structure of Surfaces II”, J.F. Van der Veen, M.A. Van Hove, eds., (Springer Verlag), 167, 1987.Google Scholar