Surface films on corroded binary copper alloys

Abstract Auger electron spectroscopy has been used to examine the compositions of oxide films formed when four dilute binary copper alloys (Cu-Mn, Cu-Ti, Cu-Sn, Cu-Si) are immersed in ammoniacal Cu(II) solutions. The films formed range in composition from Cu 2 O containing a little of the alloying element M (as its oxide) to M x O containing a little oxidised Cu. The film formed on Cu-4 wt.% Mn at pH 7.3 is oxygen-deficient, and probably contains appreciable metallic Cu. A number of effects of electron bombardment on the films at low beam current densities are noted. There is no apparent relationship between the compositions of these films and the tendency of the alloys to undergo stress-corrosion cracking in these electrolytes.