Scale-Bridging Thermodynamic and Kinetic Simulation (STKS)
Intermediate Co/Ni-base model superalloys — Thermophysical properties, creep and oxidation
C. Zenk, S. Neumeier, N. M. Engl, S. G. Fries, O. Dolotko, M. Weiser, S. Virtanen, M. Göken.
Scripta Materialia, 112, 83-86, (2016)
The mechanical properties of γ′-strengthened Co–Ni–Al–W–Cr model superalloys extending from pure Ni-base to pure Co-base superalloys have been assessed. Differential scanning calorimetry measurements and thermodynamic calculations match well and show that the γ′ solvus temperature decreases with increasing Co-content. The γ/γ′ lattice misfit is negative on the Ni- and positive on the Co-rich side. High Ni-contents decelerate the oxidation kinetics up to a factor of 15. The creep strength of the Ni-base alloy increases by an order of magnitude with additions of Co before it deteriorates strongly upon higher additions despite an increasing γ′ volume fraction.
Keyword(s): cobalt; nickel; superalloy, creep; neutron diffraction