Grain boundary segregation and precipitation in an Al-Zn-Mg-Cu alloy

High strength Al-alloys are highly susceptible to intergranular embrittlement, which severely limits their lifetime. This article summarizes our recent work on the effect of solute segregation in the precipitation behavior at grain boundaries (GBs) compared to the grain interiors. Solute segregation could accelerate the precipitation behavior at GBs, which causes the formation of coarse precipitates and precipitate free zones along GBs. Furthermore, the interplay of solute segregation and the local structure at GBs has been considered. We show that the distinct segregation and precipitation behavior occurs within the same GB, which makes the GB excess of solutes at one facet significantly higher than the other facet. This paper enriches the current understanding on the role of chemistry and structure at GBs related to intergranular fracture and corrosion resistance in high strength Al-alloys.