Published online by Cambridge University Press: 31 January 2011
A systematic experimental study of solute migration during thermal annealing and oxidation of type 2011 aluminum alloy is described. Specimens of this alloy were implanted with Ti, Cr, or Al ions to doses in the range 2 × 1015–2 × 1017 ions cm-2. The implanted substrates were annealed at 500 °C in vacuum or an oxygen atmosphere and analyzed with Rutherford backscattering and scanning electron microscopy. Changes to the alloy composition resulting from segregation of constituents in the near surface region occurred for both implanted and unimplanted specimens, though the effect was substantially more pronounced following implantation. In addition, segregation was affected by the type and dose of the implanted ion. For the Ti implants under oxidizing conditions, the Ti ions were found to diffuse toward the surface and form a thick oxide layer. Segregation of Cu and Pb/Bi then occurred below this oxide layer. In contrast, implanted Cr ions under similar conditions were observed to diffuse into the substrate with only a thin oxide layer being formed at the surface. Consequently, Cu and Pb/Bi segregated close to the surface.