Concentration Change of Sn in the Surface Layers of Cu–Sn Alloy System due to Friction

Changes in the composition and structure of Cu-5w%Sn alloy system due to friction or heating were examined with X-ray technique, electron probe microanalysis and Auger emission spectroscopy. It was found that the intensities of Auger spectra of Sn on the surface increased rapidly with friction process or heating temperature, and that after heating at 500°C for 30 min their maximum was about 40% of that from pure Sn. The structural changes of the surface of polycrystalline ε-Cu3Sn and η-Cu6Sn5 due to friction were examined. The results obtained were as follows: (1) the structure of ε-Cu3Sn remained unaffected by the friction and (2) η-Cu6Sn5 decomposed partially into ε-Cu3Sn during the friction process, and a thin film of Sn arose from its decomposition at the surface.