Effects of alloying elements on microstructure, hardness and growth rate of compound layer in gaseous-nitrided ferritic alloys

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Abstract

Pure iron and FeM (M = Mo, Si, Mn, Cr, Al, V) binary ferritic alloys were nitrided at 843 K for various times. Phase constituent, hardness distribution and growth rate of the compound layer are investigated by means of X-ray diffraction, EBSD, EPMA, 3DAP and nanoindentation. In pure iron, ¾ and £ A (beneath ¾) form on the surface, and voids form along the interface. The hardness of £ A is higher than ferrite matrix, while void formation causes softening of compound layer. Although alloying effects on the hardness of compound layer are small, Si, V and Al additions suppress the formation of voids, and therefore the softening is also contained. All the elements investigated increase growth rate of compound layers. Especially the Si, V and Al additions significantly accelerate their growth rate due to the presence of excess nitrogen in compound layer. However, in the case of Al-added specimen, the growth layer becomes sluggish at longer nitriding time, presumably because of the extensive precipitation of AlN into the diffusion layer.

Original languageEnglish
Pages (from-to)596-602
Number of pages7
JournalMaterials Transactions
Volume62
Issue number5
DOIs
Publication statusPublished - 2021

Keywords

  • Alloying elements
  • Compound layer
  • Electron backscatter diffraction (EBSD)
  • Nitriding
  • Three-dimensional atom probe (3DAP)

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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