Lattice misfit during ageing of a polycrystalline nickel-base superalloy

Research output: Contribution to journalArticlepeer-review


  • L. Yan
  • E. A. Marquis
  • L. D. Connor
  • J. J. Ciardiello
  • A. D. Evans
  • H. J. Stone

Colleges, School and Institutes

External organisations

  • University of Michigan
  • Diamond Light Source
  • University of Cambridge
  • Institut Laue-Langevin


The temporal evolution of the lattice parameters and lattice misfit of an advanced polycrystalline nickel-base superalloy have been studied in situ during an ageing heat treatment using synchrotron X-ray diffraction. During ageing, the γ and γ′ lattice parameters were both observed to decrease, a trend that cannot be attributed to a loss of coherency alone. Phase-extracted γ′ replicated this behaviour. Atom probe tomography was used to measure the compositional changes between the start and end of the ageing heat treatment. Using these data, a thermodynamic assessment was made using the software ThermoCalc of the structural change across the interface between γ and γ′. Subsequently, the unconstrained lattice parameters were estimated and were shown to be in good agreement with the X-ray diffraction measurements. Thus, the observed anomalous lattice misfit behaviour was concluded to be dominated by elemental exchange between the γ and γ′ phases during ageing.


Original languageEnglish
Pages (from-to)7791-7804
Number of pages14
JournalActa Materialia
Issue number20
Publication statusPublished - Dec 2013


  • Coarsening, Misfit, Nickel alloys, Synchrotron radiation, X-ray diffraction (XRD)