Sputtering of the intermetallic compound FeTi: Indication for dominant surface segregation effect

Compositional changes induced at the surface region of the intermetallic compound FeTi by room-temperature Ar⁺ bombardment were studied using Auger Electron Spectroscopy. The line intensities measured during sputtering reflect quite complex kinetics, and the steady-state values when compared to the bulk intensities obtained from a scribed sample reveal a significant, ion-energy dependent, enrichment of iron, whereas an opposite trend would be predicted from the pure element sputtering yields. Also, the magnitude of the effect does not correlate with the small mass difference of Ti and Fe. The only mechanism which seems to account for the sputter behaviour of FeTi is surface segregation of titanium assisted by bombardment-induced enhanced diffusion. This indirectly determined segregation trend in this system correlates well with surfacetension data of the pure elements.