In-situ Synchrotron X-ray Diffraction During Selective Laser Melting of High Entropy Alloys

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Microstructural evolution and phase stability in Nb-containing interstitial Fe-Mn-Co-Cr-C high-entropy alloys

Publication . Moura, I. A. B.; Ribamar, G. G.; Chuang, A. C.; Nunes, T. S.; Shen, Jiajia; Zhang, Wei; Rodrigues, P. Freitas; Pereira, A. B.; Pei, Yutao; Zhang, F.; Oliveira, J. P.; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier BV

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.

2025-09Artigo científico

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Fundação para a Ciência e a Tecnologia

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OE

Número da atribuição

2021.08034.BD