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 Nin-xAlx 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 Ni54Al cluster the Al impurity is located at the 12-coordinate central site, i.e., ordering predominates over segregation.