Surface Composition of a Tin-Lead Alloy

摘要

The surface and near surface composition of a single phase tin-lead alloy whose bulk composition was 99.83 at. % tin and 0.17 at. % lead has been measured as a function of temperature in vacuum and in an oxidizing ambient. In vacuum, the outer monolayer of the surface is enriched in lead at all temperatures studied (approx. = 65% at. % Pb at 23 exp 0 C). From the measured lead surface composition as a function of temperature, a heat of segregation of 4.7 kcal/mole is calculated. The data obtained in an oxidizing ambient indicate that the near surface composition is dependent on the oxygen partial pressure as well as the temperature at which the sample is annealed. (ERA citation 07:011267)