Microstructure characterization of Cu-rich nanoprecipitates in a Fe-2.5 Cu-1.5 Mn-4.0 Ni-1.0 Al multicomponent ferritic alloy

Y. R. Wen, Akihiko Hirata, Z. W. Zhang, T. Fujita, C. T. Liu, J. H. Jiang, M. W. Chen

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The evolution of precipitates in a Fe-2.5 Cu-1.5 Mn-4.0 Ni-1.0 Al multicomponent ferritic alloy during annealing at 500 °C was systematically investigated by aberration-corrected scanning transmission electron microscopy. The atomic-scale structure and chemistry characterization reveal that primary precipitates with enriched Cu, Ni, Mn and Al originate from continuous growth of B2 ordered domains in the as-quenched alloy. The formation of a Cu-rich body-centered cubic (bcc) phase takes place by the decomposition of the B2 ordered primary phase, which forms a Cu-rich bcc core and ordered B2-Ni(Al,Mn) shell. The B2 shells serve as a buffer layer to moderate the coherent strain and to prohibit the inter-diffusion between the Cu-rich precipitates and bcc-Fe matrix, giving rise to a low coarsening rate of the precipitates. The Cu-rich precipitates experience a structural transformation from bcc to 9R at a critical size of ∼6 nm during long time annealing, corresponding to obvious coarsening of the precipitates and dramatic loss in hardness of the alloy.

Original languageEnglish
Pages (from-to)2133-2147
Number of pages15
JournalActa Materialia
Issue number6
Publication statusPublished - 2013 Apr 1
Externally publishedYes



  • Core/shell precipitates
  • Fe-Cu alloy
  • Precipitation hardening
  • STEM

ASJC Scopus subject areas

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

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