Nitrogen-related short-range order in Fe-Ni-Cr austenitic stainless steels: first principles and cluster expansion study
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866912468655144960 |
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| author | Su, Tianyu Blankenau, Brian J. Kim, Namhoon Krogstad, Jessica A. Ertekin, Elif |
| author_facet | Su, Tianyu Blankenau, Brian J. Kim, Namhoon Krogstad, Jessica A. Ertekin, Elif |
| contents | Nitrogen (N) is a key alloying element that enhances the performance of Fe-Ni-Cr austenitic stainless steels, improving austenite stability, corrosion resistance, and yield strength. However, the role of N in modifying chemical ordering, particularly short-range order (SRO) and long-range order (LRO), is complex due to the multi-sublattice nature and magnetic interactions in these alloys. In this work, we combine first-principles calculations with the spin cluster expansion (spin CE) method to systematically investigate the effects of N on chemical ordering in Fe-Ni-Cr alloys. Our atomistic models confirm a strong affinity between N and Cr, which drives the formation of N-Cr SRO and, at higher N concentrations, stabilizes M4N-type ordered phases (M = metal). Monte Carlo simulations reveal that low N concentrations promote local N-Cr or N-N SRO, while increasing N content leads to the emergence of Cr-and N-rich LRO structures. We also show that the presence of N suppresses intrinsic Fe-Cr and Ni-Cr SRO by competing with these interactions, particularly at high concentrations. The impact of Cr content on ordering diminishes as N approaches its solubility limit. These findings are consistent with experimental observations in high-N austenitic steels. Finally, we discuss the influence of kinetic and magnetic effects on SRO evolution in high-N alloys. This study provides a comprehensive framework for understanding N-driven chemical ordering and offers insights into microstructural changes during nitriding processes. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_04580 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Nitrogen-related short-range order in Fe-Ni-Cr austenitic stainless steels: first principles and cluster expansion study Su, Tianyu Blankenau, Brian J. Kim, Namhoon Krogstad, Jessica A. Ertekin, Elif Materials Science Nitrogen (N) is a key alloying element that enhances the performance of Fe-Ni-Cr austenitic stainless steels, improving austenite stability, corrosion resistance, and yield strength. However, the role of N in modifying chemical ordering, particularly short-range order (SRO) and long-range order (LRO), is complex due to the multi-sublattice nature and magnetic interactions in these alloys. In this work, we combine first-principles calculations with the spin cluster expansion (spin CE) method to systematically investigate the effects of N on chemical ordering in Fe-Ni-Cr alloys. Our atomistic models confirm a strong affinity between N and Cr, which drives the formation of N-Cr SRO and, at higher N concentrations, stabilizes M4N-type ordered phases (M = metal). Monte Carlo simulations reveal that low N concentrations promote local N-Cr or N-N SRO, while increasing N content leads to the emergence of Cr-and N-rich LRO structures. We also show that the presence of N suppresses intrinsic Fe-Cr and Ni-Cr SRO by competing with these interactions, particularly at high concentrations. The impact of Cr content on ordering diminishes as N approaches its solubility limit. These findings are consistent with experimental observations in high-N austenitic steels. Finally, we discuss the influence of kinetic and magnetic effects on SRO evolution in high-N alloys. This study provides a comprehensive framework for understanding N-driven chemical ordering and offers insights into microstructural changes during nitriding processes. |
| title | Nitrogen-related short-range order in Fe-Ni-Cr austenitic stainless steels: first principles and cluster expansion study |
| topic | Materials Science |
| url | https://arxiv.org/abs/2507.04580 |