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The surface composition of compounds and alloys very generally differs from their bulk concentration. Minimization of the total energy (Gibbs free energy) leads to surface segregation in alloys with an equilibrium composition at a given temperature, characterized by the segregation energy. Ion bombardment of a solid multicomponent material can cause an altered surface concentration whose steady state value depends on the different sputtering yields of the constituents. Bombardment can further support segregation due to radiation enhanced diffusion, expressed by a diffusion coefficient. We report on experimental results, model calculations and numerical simulations concerning preferential sputtering, segregation and their combined effects for various binary systems (ie Ta(2)O(5), PdPt, CuTi, and FeAl). Detailed analysis requires surface analytical methods with different information depths, as provided by ion scattering spectroscopy (ISS) and Auger electron spectroscopy (AES). From such measurements segregation energies and diffusion coefficients can be extracted.

Additional information

Authors: TAGLAUER E, Max-Planck-Institut für Plasmaphysik, Garching bei München (DE);DU PLESSIS J, University of the Orange Free State, Department of Physics, Bloemfontein (ZA);VAN WYK G N, University of the Orange Free State, Department of Physics, Bloemfontein (ZA)
Bibliographic Reference: Article: Springer Proceedings in Physics (1996) pp. 136-145
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