High-temperature deformation mechanisms in a polycrystalline nickel-base superalloy studied by neutron diffraction and electron microscopy

E. M. Francis, B. M.B. Grant, J. Quinta Da Fonseca, P. J. Phillips, M. J. Mills, M. R. Daymond, M. Preuss

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Abstract

To study the effect of γ′ precipitate size on the deformation behaviour of a polycrystalline nickel-based superalloy, model microstructures with a unimodal γ′ size distribution were developed and subjected to loading experiments at 750 °C. Neutron diffraction measurements were carried out during loading to record the elastic lattice strain response of the γ and γ′ phase. A two-site elasto-plastic self-consistent model (EPSC) assisted in the interpretation of the elastic lattice strain response. In addition, the microstructures of the deformed specimens were analysed by (scanning) transmission electron microscopy (STEM). Excellent agreement was found between the EPSC and STEM results regarding a joint deformation of the γ and γ′ phase in the fine γ′ microstructures and for low plastic strains in the medium γ′ microstructures. With increasing γ′ size and increasing degree of plastic deformation, both experimental methodologies revealed a tendency of the two phases to deform independently.

Original languageEnglish
Pages (from-to)18-29
Number of pages12
JournalActa Materialia
Volume74
DOIs
Publication statusPublished - 1 Aug 2014
Externally publishedYes

Keywords

  • Elasto-plastic self-consistent (EPSC) model
  • High-temperature deformation
  • Neutron diffraction
  • Nickel-base superalloy
  • Transmission electron microscopy

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