Atomic recoil events at, and near to, the {001} surfaces of Ni3Al - due to elastic collisions between electrons and atoms - were simulated by using molecular dynamics to obtain the sputtering threshold energy as a function of atomic species, recoil direction and atomic layer of the primary recoil atom. The minimum sputtering energy occurred for adatoms, and was equal to 3.5 and 4.5eV for Al and Ni adatoms on the Ni–Al surface (called M), respectively, and equal to 4.5eV for both species on the pure Ni surface (called N). For atoms within the surface plane, the minimum sputtering energy was equal to 6.0eV for Al and Ni atoms in the M plane and for Ni atoms in the N surface. The sputtering threshold energy increased with increasing angle between the recoil direction and the surface normal. It was almost independent of the azimuthal angle, α. If α < 60°, it varied strongly with α when α > 60°; with a maximum at α = 45°, due to close-packed atomic chains in the surface. The sputtering threshold energy increased significantly for sub-surface recoils, except for those that generated efficient energy transfer to a surface atom via a replacement collision sequence.

Point-Defect Properties of, and Sputtering Events in, the {001} Surfaces of Ni3Al - II. Sputtering Events at and Near Surfaces. W.S.Lai, Y.N.Osetsky, D.J.Bacon: Philosophical Magazine, 2005, 85[16], 1687-700