Structural and chemical length scales at near-stationary austenite-ferrite interfaces in a model duplex stainless steel
Abstract
The structural and chemical properties of austenite/ferrite (γ/α) interfaces were investigated in a model duplex stainless steel (Fe–Cr–Ni–Mo–N) using a correlative approach combining scanning transmission electron microscopy (STEM), electron energy-loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDS), and atom probe tomography (APT). Two interface types were selected based on their orientation relationship (OR): a near-Kurdjumov-Sachs (K-S) interface and a non-K-S interface. The near K-S interface presents a planar terrace-ledge morphology with atomically sharp structural transitions at the terraces, whereas the non-K-S interface is rough with protrusions of 3–5 nm amplitude. In both cases, the chemical transition width measured by EELS and APT exceeds the crystallographic interface width determined from STEM imaging, indicating that chemical potential perturbations extend beyond the structural discontinuity. The OR is found to have a clear effect on the solute segregation behavior: Mo and N segregate exclusively to the non-K-S interface, while Cr segregates to both interface types. Ni shows no detectable interfacial excess at either interface. The 2D APT composition maps reveal a spatially heterogeneous distribution of Cr at the near K-S interface, with a strong spatial correlation between Cr and N enrichment attributed to their attractive thermodynamic interaction. Gibbsian interfacial excess values and segregation energies are reported for all solutes, distinguishing between effective and intrinsic contributions. Thermodynamic self-consistency of the derived segregation energies is only achieved for an interface width of 1–2 nm, consistent with the chemical width from EELS. This provides an experimentally grounded estimate of the interface width directly applicable to solute drag models of γ/α interface migration.
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BibTeX
@article{benrabah2026structural,
title = {{Structural and chemical length scales at near-stationary austenite-ferrite interfaces in a model duplex stainless steel}},
author = {Imed-Eddine Benrabah and Hui Yuan and Gwladys Steciuk and Damien Tresallet and Carmen Andrei and Hugo van Landeghem and Gianluigi Botton and Muriel Veron and Hatem Zurob},
journal = {Acta Materialia},
year = {2026},
month = oct,
doi = {10.1016/j.actamat.2026.122756},
url = {https://hal.science/hal-05793673v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Structural and chemical length scales at near-stationary austenite-ferrite interfaces in a model duplex stainless steel
AU - Imed-Eddine Benrabah
AU - Hui Yuan
AU - Gwladys Steciuk
AU - Damien Tresallet
AU - Carmen Andrei
AU - Hugo van Landeghem
AU - Gianluigi Botton
AU - Muriel Veron
AU - Hatem Zurob
PY - 2026
DA - 2026/10/12
JO - Acta Materialia
DO - 10.1016/j.actamat.2026.122756
UR - https://hal.science/hal-05793673v1
AB - The structural and chemical properties of austenite/ferrite (γ/α) interfaces were investigated in a model duplex stainless steel (Fe–Cr–Ni–Mo–N) using a correlative approach combining scanning transmission electron microscopy (STEM), electron energy-loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDS), and atom probe tomography (APT). Two interface types were selected based on their orientation relationship (OR): a near-Kurdjumov-Sachs (K-S) interface and a non-K-S interface. The near K-S interface presents a planar terrace-ledge morphology with atomically sharp structural transitions at the terraces, whereas the non-K-S interface is rough with protrusions of 3–5 nm amplitude. In both cases, the chemical transition width measured by EELS and APT exceeds the crystallographic interface width determined from STEM imaging, indicating that chemical potential perturbations extend beyond the structural discontinuity. The OR is found to have a clear effect on the solute segregation behavior: Mo and N segregate exclusively to the non-K-S interface, while Cr segregates to both interface types. Ni shows no detectable interfacial excess at either interface. The 2D APT composition maps reveal a spatially heterogeneous distribution of Cr at the near K-S interface, with a strong spatial correlation between Cr and N enrichment attributed to their attractive thermodynamic interaction. Gibbsian interfacial excess values and segregation energies are reported for all solutes, distinguishing between effective and intrinsic contributions. Thermodynamic self-consistency of the derived segregation energies is only achieved for an interface width of 1–2 nm, consistent with the chemical width from EELS. This provides an experimentally grounded estimate of the interface width directly applicable to solute drag models of γ/α interface migration.
SN - 1359-6454
ER -