Investigation of the elemental partitioning behaviour and site preference in ternary model nickel-based superalloys by atom probe tomography and first-principles calculations

Abstract

The topologically close-packed phase formation is heavily influenced by the concentrations of Co, Ru, and Cr in Ni-based superaloys. For this purpose, we investigate the partitioning behaviour and site preference of these additions in the model Ni–Al–X single crystal superalloys by atom probe tomography and first-principles calculations. Compared with the commercial multicomponent superalloys, Co and Ru still strongly partition to the phase, while Cr weakly partitions to the phase in the ternary model alloys. Based on the phase composition analyses, Ru and Cr atoms preferentially substitute for the Al sublattice sites, whereas Co atoms substitute at both Al and Ni sublattice sites in the ordered - phase. First-principles calculations on the substitutional formation energies at 0 K were performed to understand the site preference, and the partitioning coefficient of additions was given in a quantitative model. The partitioning behaviour and site preference of Co, Ru, and Cr by theoretical calculations are consistent with the experimental results.

Keywords:

• Nickel-based superalloys
• atom probe tomography (APT)
• partitioning coefficient
• first-principles calculations

Notes

The authors declare that there is no conflict of interests regarding the publication of this paper.

Supplemental data for this article can be accessed here http://dx.doi.org/10.1080/14786435.2016.1192298.

Additional information

Funding

This work was supported by the National Basic Research Program of China [‘973 Project’, Ministry of Science and Technology of China, grant number 2011CB606402]; the simulations were carried out on the ‘Explorer 100’ cluster system of Tsinghua National Laboratory for Information Science and Technology, Beijing, China.