The effect of phase chemistry on the extent of strengthening mechanisms in model Ni-Cr-Al-Ti-Mo based superalloys

A. J. Goodfellow, E. I. Galindo-Nava, K. A. Christofidou, N. G. Jones, C. D. Boyer, Tomas L Martin, P. A.J. Bagot, M. C. Hardy, H. J. Stone*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

15 Citations (Scopus)
267 Downloads (Pure)

Abstract

The exceptional mechanical properties of polycrystalline nickel-based superalloys arise through various concurrent strengthening mechanisms. Whilst these mechanisms are generally understood, consensus has yet to be established on the precise contribution of each to the overall alloy strength. Furthermore, changes in alloy chemistry influence several different mechanisms, making the assessment of individual alloying elements complex. In this study, a series of model quinary Ni-based superalloys has been investigated to systematically study the effect of varying Mo content on the contributing strengthening mechanisms. Using microstructural data, the yield strength was modelled by summing the individual effects of solid solution in both the γ and γʹ phases, coherency, grain boundary and precipitation strengthening. The total predicted yield stress increased with Mo content despite the diminishing contribution of precipitation strengthening. It is shown that solid solution strengthening of the ordered γʹ precipitate phase is a key contributor to the overall strength, and that variations in composition between the tertiary and secondary γʹ lead to significant changes in mechanical properties that should be accounted for in models of alloy strength.
Original languageEnglish
Pages (from-to)290-302
Number of pages13
JournalActa Materialia
Volume153
Early online date3 May 2018
DOIs
Publication statusPublished - 1 Jul 2018

Keywords

  • Atom probe tomography
  • Electron microscopy
  • Mechanical properties
  • Modelling
  • Superalloy

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