Characterization of AA7075/AA5356 gradient transition zone in an electron beam wire-feed additive manufactured sample

摘要

A transition zone formed using electron beam wide-feed additive deposition of AA5356 on a AA7075 substrate was investigated for microstructure, composition, tensile strength microhardness and chemical corrosion resistance. The chemical composition of the transition zone was characterized by incrementally increasing content of Mg and decreasing contents of Cu and Zn. Microstructurally there was a transition from thick intergrain intermetallic network to uniformly distributed intermetallic particles. Phase composition of the zone was represented by coarse and fine Al-Mg-Cu-Zn particles, as well as FeAl ones and Mg2Si composite particles located at the columnar grain boundaries. Microhardness and tensile strength of this zone were higher than those of pure AA5356 deposited metal. Severe intergranular corrosion was observed on the surface of the transition zone. The intensity of corrosion inversely correlated with the Mg content.