The partitioning and site preference of rhenium or ruthenium in model nickel-based superalloys: An atom-probe tomographic and first-principles study

The partitioning behavior and sublattice site preference of Re or Ru in the Ni3Al (Ll(2)) gamma'-precipitates of model Ni-Al-Cr alloys are investigated by atom-probe tomography (APT) and first-principles calculations. Rhenium and Ru are experimentally observed to partition to the gamma(fcc)-phase, which is consistent with the smaller values of the gamma-matrix Re and Ru substitutional formation energies determined by first-principles calculations. APT measurements of the gamma(fcc)-precipitate composition indicate that Re and Ru occupy the Al sublattice sites of the Ni3Al (Ll(2) ) phase. The preferential site substitution of Re and Ru at Al sublattice sites is confirmed by first-principles calculations. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2998654]