Symmetry breaking induced asymmetric dislocation-planar fault interactions in ordered intermetallic alloys

Cheng Chen, Fei Xu, Jun Song

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

In this study, we present the first comprehensive examination of symmetry breaking in the interactions between dislocation and superlattice planar faults, including anti-phase boundary (APB), complex stacking fault (CSF), superlattice intrinsic stacking fault (SISF), to reveal the underlying asymmetric dislocation reaction mechanisms depending on the sense of applied stress, employing both large-scale atomistic simulations and continuum dislocation theory. Four ordered intermetallic alloy systems including γ-Ni/γ-Ni3Al and γ-Ni/γ-Ni3Fe, γ-Al/γ-TiAl, and α-Ti/α2−Ti3Al were selected as the representative model systems, with two primary symmetry breaking effects, i.e., translational and three-fold rotational symmetry breaking considered. Detailed atomic steps of asymmetrical dislocation reactions and the corresponding asymmetrical dislocation bypassing mechanisms of precipitation have been elucidated, shown to be highly dependent on the geometrical configuration of the precipitate and the relative magnitudes of APB, CSF and SISF fault energies. A continuum model framework was then developed, which, for the first time, provides accurate and quantitative predictions of the threshold conditions triggering critical asymmetric dislocation slips, verified to be in good agreement with the simulation results. Our study also successfully reproduced the experimentally observed dislocation-induced APB-SISF transformation, with a new dislocation reaction mechanism proposed to explain the transformation process. The findings are expected to be a key enabling stepstone for future innovation in intermetallic alloys strengthened through ordered phases for advanced applications in aeronautic and automotive industries.

Original languageEnglish
Article number103982
JournalInternational Journal of Plasticity
Volume177
DOIs
StatePublished - Jun 2024

Keywords

  • Al/TiAl
  • Asymmetric deformation
  • Atomistic simulations
  • Continuum dislocation theory
  • Dislocation
  • Intermetallic alloys
  • Ni/NiAl
  • Ni/NiFe
  • Stacking fault
  • Symmetry breaking
  • Ti/TiAl

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