Abstract
The surfaces of 65/35 brasses with normal and reddish color have been studied by XPS, EPMA and X-ray diffraction. Both brasses are coverd by very thin surface films (2–3 nm thick) and reveal normal zinc contents at a depth of more than 10 μm. However, the surface region of less than 1 μm is fairly dezincified. The dezincification is most serious in the surface within a depth of 10 nm under the surface film, particularly in the reddened sample. The skin depth of light with a wavelength of 1 μm is about 4 nm for pure metallic copper and the thickness of the surface film is too small to cause the coloration. It was concluded, therefore, that the cause of the reddening is due to the enrichment of copper at the underlying alloy surface by the dezincification.
