Characterization of Thin Surface Layers Formed in Copper-Based Alloys

Abstract

An attempt has been made to describe recent systematic results on characterization of thin surface layers formed in copper-based alloys, which were exposed to mild atmospheres, such as ultra-high vacuum and low partial pressures of oxygen at a high temperature. Surface analytical techniques such as X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used for studying the thin surface layers formed in copper-based alloys. The results show that a surface-active element is segregated on the surface of copper-based alloys by annealing at high temperatures in ultra high vacuum. The selective oxidation of reactive elements was found to take place in a surface layer formed in copper-based alloys by heating under a low partial pressure of oxygen, in which matrix copper is not oxidized. In addition, the formation of a native oxide layer on the surface of copper-based alloys, which occurs by exposure to air at room temperature, is also discussed. The formation of these surface layers is interpreted on the basis of the thermodynamic character of elements in copper-based alloys.