University of Oulu

Rani, E., Singh, H., Alatarvas, T., Kharbach, M., Cao, W., Sarpi, B., Zhu, L., Niu, Y., Zakharov, A., Fabritius, T., & Huttula, M. (2022). Uncovering temperature-tempted coordination of inclusions within ultra-high-strength-steel via in-situ spectro-microscopy. Journal of Materials Research and Technology, 17, 2333–2342.

Uncovering temperature-tempted coordination of inclusions within ultra-high-strength-steel via in-situ spectro-microscopy

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Author: Rani, Ekta1; Singh, Harishchandra1,2; Alatarvas, Tuomas2,3;
Organizations: 1Nano and Molecular Systems Research Unit, University of Oulu, FIN-90014, Finland
2Centre for Advanced Steels Research, University of Oulu, FIN-90014, Finland
3Process Metallurgy Research Unit, University of Oulu, FIN-90014, Finland
4MAX IV Laboratory, Lund University, Lund, 22484, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-06-22


Despite the common challenge of investigating non-metallic inclusions within ultra-high-strength-steel (UHSS) at sub-micrometer scale via conventional methods, probing nitride inclusions at elevated temperatures is vital for guiding steel’ performance. Herein, an in-situ spectro-microscopic determination using advanced Synchrotron X-ray absorption spectroscopy (XAS) coupled with photoelectron emission microscopy (PEEM) is employed to explore the local structure and electronic properties of selective h-boron nitride (h-BN) containing inclusions (A1 and A2) embedded within steel matrix. While the variation in the relative intensity of π∗/σ∗ excitonic peaks at spatially different locations refers to the polarization and or thickness effects. Several minute features observed in the 192–195 eV energy range show oxygen (O) substituted nitrogen (N) defects (ON,2N,3N), which are more dominant in A2 inclusion. The observed dominance further explains the relatively high intense π∗ peak in A2 due to increased localization. Weak shoulder on the left side of π∗ peak in both room and high-temperature XAS spectra is ascribed to the interaction between h-BN and the local environment, such as Ca-based inclusion or steel matrix. Defects are commonly found in h-BN, and precise identification of the same is vital as they affect the overall physical, chemical, and mechanical properties. Moreover, significant changes in high-temperature B K-edge XAS spectra, such as relative intensity of π∗/σ∗ excitonic peaks at the same location and reduced intensity of defects, suggest the adjusting nature of BN inclusion, complicating their precise prediction and control towards clean steel production.

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Series: Journal of materials research and technology
ISSN: 2238-7854
ISSN-E: 2214-0697
ISSN-L: 2238-7854
Volume: 17
Pages: 2333 - 2342
DOI: 10.1016/j.jmrt.2022.01.170
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: Authors acknowledge Academy of Finland grant #311934 and Kvantum Institute, University of Oulu (Project CLEAN2STEEL) for the financial support.
Dataset Reference: Supplementary data to this article can be found online at
Copyright information: © 2022 The Author(s). This is an open access article under the CC BY-NC-ND license (