On the interstitial induced lattice inhomogeneities in nitrogen-expanded austenite

Xiao Tao, Jiahui Qi, Mark Rainforth, Allan Matthews, Adrian Leyland

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2 Citations (Scopus)
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Lattice inhomogeneities, i.e. nitrogen interstitial-induced hexagonal-close-packed martensite (HCP-εN) and shear bands, can form in face-centred cubic nitrogen-expanded austenite (FCC-γN) synthesised on Fe-Cr-Mn and Fe-Cr-Ni austenitic stainless steel (ASS) using triode-plasma nitriding (TPN). Homogenous elemental distribution between HCP-εN and FCC-γN supports the displacive shear transformation mechanism proposed for a high-Mn, low stacking fault energy ASS under nitrogen interstitial-induced deformation. While resulting from transformation-induced plasticity, HCP-εN exhibits similar lattice expansion behaviour to the parent FCC-γN. However, inhomogeneous elemental distributions in the shear bands formed in γN layers on a 400°C TPN-treated high-Ni ASS indicate local migration of substitutional elements.
Original languageEnglish
Pages (from-to)146-151
JournalScripta Materialia
Early online date3 May 2020
Publication statusPublished - Aug 2020


  • Expanded austenite
  • High-resolution electron microscopy (HREM)
  • Martensitic phase transformation
  • Nitriding
  • Shear banding


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