University of Oulu

Sasikala Devi, AA, Pallaspuro, S, Cao, W, et al. Density functional theory study of ω phase in steel with varied alloying elements. Int J Quantum Chem. 2020; 120:e26223. https://doi.org/10.1002/qua.26223

Density functional theory study of ω phase in steel with varied alloying elements

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Author: Sasikala Devi, Assa Aravindh1; Pallaspuro, Sakari2; Cao, Wei1;
Organizations: 1Nano and Molecular Systems Research Unit, University of Oulu, Oulu, Finland
2Materials and Mechanical Engineering Research Unit, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 17 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2020042019317
Language: English
Published: John Wiley & Sons, 2020
Publish Date: 2020-04-20
Description:

Abstract

The presence of a long‐abandoned hexagonal omega (ω) phase in steel samples is recently gaining momentum owing to the advances in transmission electron microscopy (TEM) measurements, even though it is already reported in other transition‐metal alloys. The stabilization of this metastable phase is mainly investigated in presence of C, even though the formation of the ω phase is attributed to the combined effect of many factors, one among which is the enrichment of solute elements such as Al, Mn, Si, C, and Cr in the nanometer‐sized regimes. The present study investigates the effect of the above alloying elements in ω‐Fe using density functional theory (DFT) calculations. It is seen that the magnetic states of the atoms play a major role in the stability of ω‐Fe. Cohesive energy calculations show that the alloying elements affect the energetics and stabilization of ω‐Fe. Further, density of states calculations reveal the variation in d‐band occupancy in the presence of alloying elements, which in turn affects the cohesive energy. Phonon band structure calculations show that only ω‐Fe with substitutional C shows positive frequencies and hence possess thermodynamic stability. Finally, we confirm the existence of ω‐Fe using TEM measurements of a steel sample containing the same alloying elements. Our results can shed light on the stabilization of the ω in other transition‐metal alloys as well, in the presence of minor alloying elements./p>

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Series: International journal of quantum chemistry
ISSN: 0020-7608
ISSN-E: 1097-461X
ISSN-L: 0020-7608
Volume: 120
Issue: 13
Article number: e26223
DOI: 10.1002/qua.26223
OADOI: https://oadoi.org/10.1002/qua.26223
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Subjects:
TEM
Funding: This work was funded by the Genome of Steel (Profile3) by the Academy of Finland through project #311934.
Copyright information: © 2020 The Authors. International Journal of Quantum Chemistry published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
  https://creativecommons.org/licenses/by/4.0/