Atomic partitioning of ruthenium in Ni-based superalloys

Abstract

The elemental partitioning characteristics of Ru additions within the microstructure of high refractory content Ni-base single crystal superalloys have been investigated using atom probe tomography (APT). Although detailed microanalysis revealed some dissolution of Ru within the ordered intermetallic γ′ precipitates, Ru was observed to preferentially partition to the disordered γ matrix. The partitioning characteristics of two nominally similar alloys with and without Ru were studied as part of this investigation. Analyses indicate that no significant changes in the partitioning characteristics of the constituent elements could be attributed to the presence of Ru for this particular set of alloys. The preferential site occupancy of Ru within the L12 lattice was also statistically quantified using ALCHEMI (atomic site location by channelling enhanced microanalysis). Interestingly, Ru exhibited a tendency to substitute for Al and occupy the corner sites in the γ′ structure.