On the microtwinning mechanism in a single crystal superalloy

D. Barba, E. Alabort, S. Pedrazzini, D. M. Collins, A. J. Wilkinson, P. A.J. Bagot, M. P. Moody, C. Atkinson, A. Jérusalem, R. C. Reed*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


The contribution of a microtwinning mechanism to the creep deformation behaviour of single crystal superalloy MD2 is studied. Microtwinning is prevalent for uniaxial loading along 〈011〉 at 800°C for the stress range 625 to 675 MPa and 825°C for 625 MPa. Using quantitative stereology, the twin fraction and twin thickness are estimated; this allows the accumulated creep strain to be recovered, in turn supporting the role of the microtwinning mode in conferring deformation. Atom probe tomography confirms the segregation of Cr and Co at the twin/parent interface, consistent with the lowering of the stacking fault energy needed to support twin lengthening and thickening. A model for diffusion-controlled growth of twins is proposed and it is used to recover the measured creep strain rate. The work provides the basis for a thermo-mechanical constitutive model of deformation consistent with the microtwinning mechanism.

Original languageEnglish
Pages (from-to)314-329
Number of pages16
JournalActa Materialia
Publication statusPublished - 15 Aug 2017


  • Creep
  • Diffusion
  • Microtwinning
  • Segregation
  • Superalloy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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