Superior high-temperature mechanical properties and microstructural features of LPBF-printed In625-based metal matrix composites
Abstract
The growing demands for high-temperature materials, especially in aerospace and energy production, compel thorough explorations of innovative materials. Here, we demonstrate significantly enhanced high-temperature mechanical properties of Inconel 625 (In625) based metal matrix composites (MMCs) fabricated by laser powder bed fusion (LPBF) additive manufacturing. The MMC feedstocks for LPBF were fabricated with fine ceramic particles (i.e., titanium diboride (TiB2), titanium carbide (TiC), zirconium diboride (ZrB2) and zirconium carbide (ZrC)) separately mixed with In625 powders. Among the printed specimens, the In625 + TiB2 showed an exceptional strength-ductility combination at 800 °C as well as an outstanding creep resistance at 800 °C under 150 MPa tensile stress. The detailed microstructural characterization, along with thermodynamic calculation and atomic simulations, reveal that the addition of TiB2 results in the formation of serrated grain boundaries, (Cr, Mo)-boride phases near the grain boundaries, and nano-dispersed (Ti, Al, Nb)-oxide phases within the matrix. These features effectively suppress the formation of detrimental high-temperature phases and enhance the material’s high-temperature properties. Beyond amplifying the inherent thermal attributes of In625 superalloy, the research highlights the transformative potential of boride doping and the composition design of MMCs specifically for the LPBF process.
Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgment Financial support at MIT was provided by Eni S.p.A. through the MIT Energy Initiative and ARPA-E (DE-AR0001434). GDS acknowledges support from the National Research Foundation of Korea (No. RS-2024-00406086). W.C. acknowledges the support from the US National Science Foundation (DMR-2238204). S.K. acknowledges support from the National Research Foundation of Korea (NRF-2021M2D2A2076378). We thank Dave Follette at the Advanced Digital Design and Fabrication facility at the University of Massachusetts, Amherst for support with LPBF fabrication. TEM studies were performed at MIT.nano. Author contributions statement E.T. and J.S.B. analyzed the results, characterized the materials, and wrote; H.K. performed creep tests, characterized crept sample, and wrote; K.H.L. performed HT tensile tests and fracture surface analysis; J. Liu performed RT tensile tests; T.D.D. developed the hybrid Monte-Carlo-molecular-dynamics routine and provided preliminary atomistic insights; S.Y.K. carried out TEM sample preparation; M.A. supported the materials characterizations study; A.P. performed TEM studies; W.C. oversaw the study and provided editing; A-.J.H. oversaw the study and provided editing; J.H.K. oversaw the study and provided editing; C.S.O. performed thermodynamic calculations; J.W.P. oversaw the study and provided editing; F.S. performed TEM studies on tensile deformed specimens and provided editing; S.K., G.D.S. and J. Li conceived the project idea, oversaw the study and provided editing. Declaration of generative AI and AI-assisted technologies in the writing process During the preparation of introduction EMRE TEKOGLU used ChatGPT (GPT-4, OpenAI) in order to improve the readability. After using this tool/service, all of the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.