Composition-dependent variation of magnetic properties and interstitial ordering in homogeneous expanded austenite

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Abstract

The crystal structure and magnetic properties of austenitic stainless steel with a colossal interstitial content, so-called expanded austenite, are currently not completely understood. In the present work, the magnetic properties of homogeneous samples of expanded austenite, as prepared by lowerature nitriding of thin foils, were investigated with magnetometry and Mössbauer spectroscopy. At room temperature, expanded austenite is paramagnetic for relatively low and for relatively high nitrogen contents (yN = 0.13 and 0.55, respectively, where yN is the interstitial nitrogen occupancy), while ferromagnetism is observed for intermediate nitrogen loads. Spontaneous volume magnetostriction was observed in the ferromagnetic state and the Curie temperature was found to depend strongly on the nitrogen content. For the first time, X-ray diffraction evidence for the occurrence of long-range interstitial order of nitrogen atoms in expanded austenite was observed for high nitrogen contents.
Original languageEnglish
JournalActa Materialia
Volume106
Pages (from-to)32-39
Number of pages8
ISSN1359-6454
DOIs
Publication statusPublished - 2016

Keywords

  • Low temperature surface hardening
  • Gas nitriding
  • Expanded austenite
  • Magnetostriction
  • Mössbauer spectroscopy

Cite this

@article{0e802aadfab74d66a09d72f7a460473b,
title = "Composition-dependent variation of magnetic properties and interstitial ordering in homogeneous expanded austenite",
abstract = "The crystal structure and magnetic properties of austenitic stainless steel with a colossal interstitial content, so-called expanded austenite, are currently not completely understood. In the present work, the magnetic properties of homogeneous samples of expanded austenite, as prepared by lowerature nitriding of thin foils, were investigated with magnetometry and M{\"o}ssbauer spectroscopy. At room temperature, expanded austenite is paramagnetic for relatively low and for relatively high nitrogen contents (yN = 0.13 and 0.55, respectively, where yN is the interstitial nitrogen occupancy), while ferromagnetism is observed for intermediate nitrogen loads. Spontaneous volume magnetostriction was observed in the ferromagnetic state and the Curie temperature was found to depend strongly on the nitrogen content. For the first time, X-ray diffraction evidence for the occurrence of long-range interstitial order of nitrogen atoms in expanded austenite was observed for high nitrogen contents.",
keywords = "Low temperature surface hardening, Gas nitriding, Expanded austenite, Magnetostriction, M{\"o}ssbauer spectroscopy",
author = "Brink, {Bastian K.} and Kenny St{\aa}hl and Christiansen, {Thomas Lundin} and Cathrine Frandsen and Hansen, {Mikkel Fougt} and Somers, {Marcel A. J.}",
year = "2016",
doi = "10.1016/j.actamat.2015.12.043",
language = "English",
volume = "106",
pages = "32--39",
journal = "Acta Materialia",
issn = "1359-6454",
publisher = "Pergamon Press",

}

TY - JOUR

T1 - Composition-dependent variation of magnetic properties and interstitial ordering in homogeneous expanded austenite

AU - Brink, Bastian K.

AU - Ståhl, Kenny

AU - Christiansen, Thomas Lundin

AU - Frandsen, Cathrine

AU - Hansen, Mikkel Fougt

AU - Somers, Marcel A. J.

PY - 2016

Y1 - 2016

N2 - The crystal structure and magnetic properties of austenitic stainless steel with a colossal interstitial content, so-called expanded austenite, are currently not completely understood. In the present work, the magnetic properties of homogeneous samples of expanded austenite, as prepared by lowerature nitriding of thin foils, were investigated with magnetometry and Mössbauer spectroscopy. At room temperature, expanded austenite is paramagnetic for relatively low and for relatively high nitrogen contents (yN = 0.13 and 0.55, respectively, where yN is the interstitial nitrogen occupancy), while ferromagnetism is observed for intermediate nitrogen loads. Spontaneous volume magnetostriction was observed in the ferromagnetic state and the Curie temperature was found to depend strongly on the nitrogen content. For the first time, X-ray diffraction evidence for the occurrence of long-range interstitial order of nitrogen atoms in expanded austenite was observed for high nitrogen contents.

AB - The crystal structure and magnetic properties of austenitic stainless steel with a colossal interstitial content, so-called expanded austenite, are currently not completely understood. In the present work, the magnetic properties of homogeneous samples of expanded austenite, as prepared by lowerature nitriding of thin foils, were investigated with magnetometry and Mössbauer spectroscopy. At room temperature, expanded austenite is paramagnetic for relatively low and for relatively high nitrogen contents (yN = 0.13 and 0.55, respectively, where yN is the interstitial nitrogen occupancy), while ferromagnetism is observed for intermediate nitrogen loads. Spontaneous volume magnetostriction was observed in the ferromagnetic state and the Curie temperature was found to depend strongly on the nitrogen content. For the first time, X-ray diffraction evidence for the occurrence of long-range interstitial order of nitrogen atoms in expanded austenite was observed for high nitrogen contents.

KW - Low temperature surface hardening

KW - Gas nitriding

KW - Expanded austenite

KW - Magnetostriction

KW - Mössbauer spectroscopy

U2 - 10.1016/j.actamat.2015.12.043

DO - 10.1016/j.actamat.2015.12.043

M3 - Journal article

VL - 106

SP - 32

EP - 39

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

ER -