Segregation of Sn and Sb in a ternary Cu(1 0 0)SnSb alloy

Abstract

Surface segregation studies of Sn and Sb in Cu(1 0 0)–0.14 at.% Sn–0.12 at.% Sb ternary alloy, have been done by making use of Auger Electron Spectroscopy. The method of Linear Temperature Ramp (LTR) was employed, whereby the sample was heated and cooled linearly at a constant rate. The positive heating rate showed both a kinetic segregation profile, as well as a narrow equilibrium segregation region, at higher temperatures. The equilibrium segregation profile was extended by cooling the sample. Sn was first to segregate to the surface due to its higher diffusion coefficient, mainly from a smaller activation energy E Sn. Sb, due to its higher segregation energy, eventually replaced Sn from the surface. The modified Darken model was used to simulate the profile yielding the following segregation parameters: D o(Sn) = 6.3 × 10 −6 m 2/s, D o(Sb) = 2.8 × 10 −5 m 2/s; E Sn = 175.4 kJ/mol, E Sb = 186.3 kJ/mol; Δ G Sn ° = 64.2 kJ / mol , Δ G Sb ° = 84.3 kJ / mol ; Ω Cu–Sn = 3.4 kJ/mol, Ω Cu–Sb = 15.9 kJ/mol and Ω Sn–Sb = −5.4 kJ/mol.