Thermodynamic assessment of the Co-Ta system

Peisheng Wang; Jörg Koßmann; Ursula R Kattner; Mauro Palumbo; Thomas Hammerschmidt; Gregory B Olson

doi:10.1016/j.calphad.2018.12.002

Thermodynamic assessment of the Co-Ta system

CALPHAD. 2019:64:10.1016/j.calphad.2018.12.002. doi: 10.1016/j.calphad.2018.12.002.

Authors

Peisheng Wang¹, Jörg Koßmann², Ursula R Kattner³, Mauro Palumbo², Thomas Hammerschmidt², Gregory B Olson¹

Affiliations

¹ Center for Hierarchical Materials Design (CHiMaD), Northwestern University, 2205 Tech Drive, Evanston, IL 60208, United States.
² Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, 44801 Bochum, Germany.
³ Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8555, Gaithersburg, MD 20899, United States.

Abstract

The Co-Ta system has been reviewed and the thermodynamic description was re-assessed in the present work. DFT (density functional theory) calculations considering spin polarization were performed to obtain the energies for all end-member configurations of the C14, C15, C36 and μ phases for the evaluation of the Gibbs energies of these phases. The phase diagram calculated with the present description agrees well with the experimental and theoretical data. Considering the DFT results was essential for giving a better description of the μ phase at lower temperatures.

Keywords: CALPHAD; Co-based superalloys; TCP phase; γ-γ’.

Grants and funding

9999-NIST/Intramural NIST DOC/United States