Composition of the (110) surface of the Fe-Ni 34 at.% alloy: a study by low-energy ion scattering

The composition of the (110) surface of the Fe-Ni 34 at.% alloy has been de termined by means of low-energy ion scattering (LEIS). Since the masses of the iron and nickel nuclides ale rather close, a curve fitting procedure wa s needed to determine the contribution of the two metals to the LEIS signal . The LEIS measurements have been performed in a temperature range between room temperature and 850 E;, Shadow cone effects were exploited, measuring the LEIS: spectra with the inn beam incident along appropriate azimuthal di rection, in order to determine the composition of the topmost layer only, W e found that the surface concentration of nickel increases for increasing t emperatures. At 850 K the composition of the topmost layer is 41 +/- 2 at.% of Ni, (C) 2001 Elsevier Science B.V. All lights reserved.