DOE OSTI · 2583941
Microstructural evolution and phase stability in Nb-containing interstitial Fe-Mn-Co-Cr-C high-entropy alloys: An in-situ synchrotron X-ray diffraction study during laser melting
Abstract
The influence of Nb on phase stability and microstructural evolution in an interstitial Fe-Mn-Co-Cr-C high-entropy alloy was investigated using in-situ synchrotron X-ray diffraction (SXRD) during laser melting. Scheil-Gulliver simulations predict the formation of σ and γ-f.c.c. phases in all three alloys, along with NbC in Nb-containing compositions. SXRD confirmed the presence of most predicted phases, but the σ phase was absent. Nb promotes crystallite refinement and increases dislocation density, though excessive additions reduce refinement efficiency due to solubility limits and secondary phase formation. Furthermore, Nb addition also enhances ε-h.c.p. phase formation by reducing stacking fault energy through NbC-induced carbon depletion. Analysis of intensity peak evolution reveals that Nb alters preferred grain orientations, reducing {111} γ intensity while enhancing {220} γ , leading to a more isotropic grain distribution. Overall, Nb plays a key role in phase selection, microstructure refinement, and preferred orientation evolution, allowing the tailored microstructure of high-entropy alloys via rapid solidification.
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Moura, I. A. B. [Universidade NOVA de Lisboa, Caparica (Portugal); University of Coimbra (Portugal)] (ORCID:0000000200246110), Ribamar, G.G. [Universidade NOVA de Lisboa, Caparica (Portugal); University of Aveiro (Portugal)] (ORCID:0000000180003081), Chuang, A. C. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:000000030295381X), Nunes, T. S. [Military Institute of Engineering - IME, Rio de Janeiro (Brazil)], Shen, Jiajia [Universidade NOVA de Lisboa, Caparica (Portugal)], Zhang, Wei [University of Groningen, Nijenborgh (The Netherlands)], Rodrigues, P. Freitas [University of Coimbra (Portugal)] (ORCID:0000000176166793), Pereira, A. B. [University of Aveiro (Portugal)] (ORCID:0000000183425116), Pei, Yutao [University of Groningen, Nijenborgh (The Netherlands)], Zhang, F. [National Institute of Standards and Technology, Gaithersburg, MD (United States)], Oliveira, J. P. [Universidade NOVA de Lisboa, Caparica (Portugal)]. 2025-08-04. Microstructural evolution and phase stability in Nb-containing interstitial Fe-Mn-Co-Cr-C high-entropy alloys: An in-situ synchrotron X-ray diffraction study during laser melting. https://doi.org/10.1016/j.mtla.2025.102512
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