Examination of Aluminum Copper Films during Anodic Oxidation: I . Corrosion Studies

Abstract

Aluminum copper films in the range of 1–70 atom percent (a/o) Cu prepared by vapor deposition were examined in buffer solutions of pH 5.0, 6.0, and 9.2. Films with a low copper content (≤10 a/o) show similar corrosion properties as pure aluminum in weakly acid solutions. The formation of a layer of nonporous aluminum oxide leads to anodization up to a maximum potential of some 10V at which point the film is destroyed locally. For higher copper contents (≥40 a/o) the oxygen evolution cannot be prevented and only brittle noncontinuous oxide films are formed. These metal films have similar corrosion properties to those of pure copper. At the polarization curves obtained are closely related to those of pure copper.