American Physical Society, Physical Review Letters, 6(78), p. 1058-1061, 1997
DOI: 10.1103/physrevlett.78.1058
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Aluminum surface segregation in Ni-9% Al as studied by low-energy Auger electron spectroscopy is characterized by quite low equilibrium levels that increase with temperature, in contrast to predictions of Bragg-Williams–type theories. The free-energy cumulant expansion approach, adapted for surface segregation, reveals that short-range order can induce significant suppression of solute segregation, depending mainly on the solvent-solute interaction strength. The diminution of the effect with increasing temperature leads to anomalous increase of equilibrium segregation, in agreement with the Ni-Al experiments.