Non-Schmid response of Fe3Al: The twin-antitwin slip asymmetry and non-glide shear stress effects

S. Alkan, H. Sehitoglu

Research output: Contribution to journalArticlepeer-review


The non-Schmid effects in DO3 ordered Fe3Al (DO3-Fe3Al) are investigated by utilizing experimental measurements of the onset of slip and atomistic scale simulations to study slip directionality and core effects. Uniaxial tension and compression experiments were conducted on DO3-Fe3Al single crystals utilizing high resolution Digital Image Correlation (DIC) to measure local slip strain evolution. The measured critical resolved shear stress (CRSS) values exhibited close agreement with the theoretical values upon developing a modified Peierls-Nabarro (P-N) formalism relying on molecular dynamics (MD) simulation results. Both experimental and theoretical values indicate the break-down of Schmid Law due to two factors: the role of non-glide shear (NGS) stress component acting on the glide plane, called the NGS effect, and twinning-antitwinning asymmetry, termed the TA effect. To ascertain the role of NGS stress component on the dislocation core structures, molecular statics (MS) simulations were conducted upon imposing elastic-anisotropic dislocation displacement fields with Eshelby-Stroh formalism. Both experimental measurements and modified P-N calculations confirm that the applied NGS stress component is as important as TA slip asymmetry on the break-down of Schmid Law in CRSS values. The calculated core spreading suggests that the extent of the relative displacements on {110} family planes, favoring either twinning or antitwinning shear, can significantly contribute to the non-Schmid behavior of DO3-Fe3Al with the accompanying elastic shear coupling between NGS stress component and glide shear (GS) strain. Further extension of the modified P-N formalism towards yielding behavior at continuum scale is also discussed.

Original languageEnglish (US)
Pages (from-to)550-566
Number of pages17
JournalActa Materialia
StatePublished - Feb 15 2017


  • Atomistic modelling
  • DIC
  • FeAl
  • Non-glide stresses
  • Schmid law

ASJC Scopus subject areas

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


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