Atom-Probe Tomographic Study of ¿/¿' 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 composition and partitioning behavior of the two-phase ɣ(f.c.c.)/ɣ'(L12) microstructure. The APT composition of the ɣ-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 ɣ'(L12) precipitates (Co-10.03Al-12.48W at.%) is slightly richer in W and Al, and leaner in Co. Partitioning coefficients and Al interfacial excess have also been calculated.