Effects of rhenium addition on the temporal evolution of the nanostructure and chemistry of a model Ni–Cr–Al superalloy. I: Experimental observations

The temporal evolution of the nanostructure and chemistry of a model Ni–8.5 at.% Cr–10 at.% Al alloy, with the addition of 2 at.% Re, aged at 1073 K from 0.25 to 264 h, was studied. Transmission electron microscopy and atom-probe tomography were used to measure the number density and mean radius of the γ′ (L1₂ structure)-precipitates and the chemistry of the γ′-precipitates and the γ (face-centered cubic)-matrix, including the partitioning behavior of all alloying elements between the γ- and γ′-phases and the segregation behavior at γ/γ′ interfaces. The precipitates remained spheroidal for an aging time of up to 264 h and, unlike commercial nickel-based superalloys containing Re, there was not confined (nonmonotonic) Re segregation at the γ/γ′ interfaces.