Change of oxide film and concentration of copper on pickled Al-4.5%Mg-0.3%Cu alloy

Abstract

The structure of the oxide film and the enrichment of copper on the surface of an Al-4.5%Mg-0.3%Cu alloy pickled in sulfuric and nitric acid were investigated using GDS, XPS and SIMS techniques. The outside MgO layer of 10nm in thickness composed of high MgO and Al₂O₃ On the alloy surface after solution annealing was removed within a few seconds in the pickling solution. Then, the Al-4.5%Mg-0.3%Cu alloy slowly dissolved in the solution with the activation energy of 46±3KJ•mol^-1. copper in the alloy became concentrated on the surface in proportion to the weight loss of the Al-4.5%Mg-0.3%Cu alloy in pickling.