Surface segregation and preferential sputtering in CoNi alloys: Computer simulation of Auger spectra

Abstract The phenomena of surface segregation and preferential sputtering have been investigated in the CoNi alloy system where previous results have been contradictory. Six alloys covering the whole solid solution range were annealed at 853 K and quenched to give equilibrium segregated surfaces. Computer simulation methods were employed to analyze spectra in both energy windows significant to the system and results are reported with explanations of previous discrepancies. Shown is the fact that Ni both preferentially sputters and segregates over the whole composition range. The segregation is only truly obvious in low energy (M 2,3 M 4,5 M 4,5 transisitions) spectra as it is a monolayer phenomenon and higher energy peaks are not surface sensitive enough.