Effects of minor Cu additions on a Zn-modified Al-5083 alloy

The stress corrosion cracking (SCC) problems in aluminum alloys of the 5000 series have largely been attributed to intergranular failure due to dissolution or weakening of Mg-rich grain boundary phases that form. An investigation is made into the characteristics of the grain boundary phase following measured additions of copper to a zinc-modified Al-5083 alloy. Compositional alterations to the grain boundary phase that forms are demonstrated in the presence of copper additions, but a threshold level exists whereby an additional, potentially corrosion-prone, Cu-based phase may form in grain interiors.