Slip delocalization and diffusion mediated carbide formation during fatigue of a nickel-base superalloy

Yejun Gu, Jean Charles Stinville, Patrick G. Callahan, McLean P. Echlin, Tresa M. Pollock, Jaafar A. El-Awady

Research output: Contribution to journalArticlepeer-review

Abstract

Fatigue crack initiation at high temperatures occurs at microscopic fatigue shear bands that form near twin boundaries in polycrystalline nickel-base superalloys that contain minimal metallurgical defects. The associated dislocation sub-structure is complex and dependent on thermal and mechanical conditions. Here we show the formation of fine-scale carbide precipitates along these fatigue shear bands in a nickel-base superalloy during fatigue above 650 °C. The formation of carbide precipitates is studied using calculations of bulk and pipe diffusion. The contribution of pipe diffusion is observed to be critical in the formation of fine-scale carbides and occurs coincident with the delocalization of slip during fatigue.

Original languageEnglish (US)
Article number106077
JournalInternational Journal of Fatigue
Volume145
DOIs
StatePublished - Apr 2021
Externally publishedYes

Keywords

  • Bulk and pipe diffusion
  • Carbide precipitation
  • Coherent twin boundary
  • Microscopic fatigue shear band
  • Persistent slip band
  • René 88DT nickel-base superalloy

ASJC Scopus subject areas

  • Modeling and Simulation
  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering

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