Bulk ordering and surface segregation in Ni50Pt50 - art. no. 035421

Interatomic interactions obtained from the effective screened generalized-p erturbation method have been applied in Monte Carlo simulations to derive t he bulk and surface-alloy configurations for Ni50Pt50 The calculated order- disorder transition temperature and short-range order parameters in the bul k compare well with experimental data. The surface-alloy compositions for t he (111) and (110) facets above the ordering transition temperature are als o found to be in a good agreement with experiments. It is demonstrated that the segregation profile at the (110) surface of NiPt is mainly caused by t he unusually strong segregation of Pt into the second layer and the interla yer ordering due to large chemical nearest-neighbor interactions.