E. Schmidt and P.D. Bristowe
Sponsors: EPSRC and Rolls Royce PLC
- Atomistic calculations of faulted superlattice structures, precipitates and interfaces.
- Effect of alloying additions (Ti, Ta, W).
- Collaboration with the Rolls-Royce UTC
Research Highlight
Thermodynamic stability and electronic structure of η-Ni6Nb(Al,Ti) from first principles
N. Eurich and P. D. Bristowe, Scripta Mater. 77, 37-40 (2014)
First principles calculations in combination with special quasirandom structures are used to investigate the thermodynamic stability and electronic structure of a partially ordered hexagonal phase with chemistry Ni6Nb(Al,Ti) observed in Allvac 718Plus. The results agree with the experimental observations by confirming the structural stability of the alloy over a wide range of compositions. At finite temperature vibrational and configurational contributions to the free energy stabilise a competing orthorhombic phase which for high Ti concentrations is shown to become energetically favourable.
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| First principles formation enthalpies of Ni6NbTi1-xAlx for various structures as a function of Ti concentration. |