Atom-probe tomographic study of γ/γ′ interfaces and compositions in an aged Co–Al–W superalloy

Atom-probe tomography (APT) is utilized to investigate, in a Co–9.7Al–10.8W at.% alloy aged at 900 °C for ∼1000 h, the phase compositions and partitioning behavior of the two-phase γ(face-centered cubic)/γ′(L12) microstructure. The APT composition of the γ-matrix (Co–8.97Al–5.69W at.%) agrees well with a previously reported measurement made by energy-dispersive X-ray spectroscopy; however, the composition of the γ′(L12) precipitates (Co–10.03Al–12.48W at.%) is slightly richer in W and Al, and leaner in Co. Partitioning coefficients and Al interfacial excesses are also calculated.