Abstract: Under vacuum condition, with CuO as oxidizer, Al₂O₃/Cu surficial composites layer can be prepared through internal oxidation of Cu-Al alloy at certain temperatures. At low internal oxidation temperatures, there are more Al₂O₃ particles on the boundary than in the copper grains. At higher temperatures, Al₂O₃ particles distribute homogeneously. With the increasing of aluminium content, the depth of the composite layer reduces and the microhardness increases.