SURFACE STRUCTURE AND CHEMICAL COMPOSITION IN NiAl.

We have studied a computer simulations of the surface structure and chemical composition in NiAl for three low index surface orientations and three bulk compositions. We have applied a grand canonical Monte Carlo method in conjuction with a embedded atom potential fit to a large database. We found that the chemical composition of the (110) surface is very close to the bulk composition. For the (100) and (111) surface orientations, the Al termination contains some percentage of Ni atoms in the form of antisites and for the (111) orientation also a significant amount of surface vacancies and adatoms exist. The Ni termination of both surfaces are unstable and transform to Al terminations. [ABSTRACT FROM AUTHOR]