Grain boundary diffusion of Fe in ultrafine-grained nanocluster- strengthened ferritic steel

R. Singh, J. H. Schneibel, S. Divinski, G. Wilde

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Grain boundary diffusion of Fe in nanocluster-strengthened ferritic steel (Fe-14Cr-3W-0.4Ti-0.25Y2O3 in wt.%) has been investigated. The steel was produced by mechanical alloying followed by hot extrusion. The final grain size was ∼200 nm. The diffusivity of Fe was measured within the temperature range 423-820 K. The grain boundary penetration at lower temperatures revealed a specific time dependence, which indicates a residual interconnected porosity in the ferritic steel. In order to quantify the percolating porosity, conventional radiotracer (59Fe) diffusion measurements were combined with a study of room temperature penetration of liquid 110mAg solution to distinguish between solid-state diffusion along boundaries and penetration along the surface of interconnected cavities. The presence of porosity affected the diffusion process, introducing a hierarchy of internal interfaces. The grain boundary diffusion coefficient and the diffusivity along internal surfaces were determined in the so-called type C-C, C-B and B-B kinetic regimes of interface diffusion in a hierarchical microstructure. Using the residual activity method and a 65Zn tracer, the volume fraction of the percolating porosity was estimated to be 0.6%.

Original languageEnglish
Pages (from-to)1346-1353
Number of pages8
JournalActa Materialia
Volume59
Issue number4
DOIs
Publication statusPublished - Feb 2011

Keywords

  • Grain boundary
  • Grain boundary diffusion
  • Mechanical alloying
  • Oxide dispersion strengthening

ASJC Scopus subject areas

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

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