Computer simulation of the ground-state atomic configurations of Ni-Al clusters using the embedded-atom model

Using the Voter and Chen version of the embedded-atom model, we performed molecular-dynamics simulations to determine the ground-state atomic configurations of ${\mathrm{Ni}}_{\mathit{n}\mathrm{-}\mathit{x}}$ ${\mathrm{Al}}_{\mathit{x}}$ clusters (n=13, 19, and 55) for all concentrations x. The lowest-energy structures of both the bimetallic and the pure (x=0 and n) clusters are icosahedral. In general, there is a tendency for Al atoms to be segregated at the surfaces of the bimetallic clusters, although this effect can coexist with ordering. However, in the large ${\mathrm{Ni}}_{54}$Al cluster the Al impurity is located at the 12-coordinate central site, i.e., ordering predominates over segregation. © 1996 The American Physical Society.