Atomic recoil events at and near {001} surfaces of Ni3Al due to elastic collisions between electrons and atoms were simulated by 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 3.5 and 4.5eV for Al and Ni adatoms on the Ni–Al surface (denoted ‘M'), respectively, and 4.5eV for both species on the pure Ni surface (denoted ‘N'). For atoms within the surface plane, the minimum sputtering energy was 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, θ, between the recoil direction and surface normal, and was almost independent of the azimuthal angle, φ. If θ<60°; it varied strongly with φ when θ>60°, with a maximum at φ = 45° due to <110> 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 by a replacement collision sequence.

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