Ultrafine eutectic Ti-Fe-based alloys processed by additive manufacturing – A new candidate for high temperature applications

Applied Materials Today, vol. 20, pp. 100767

Abstract

The development of metals tailored to the metallurgical conditions of laser-based additive manufacturing is crucial to advance the maturity of these materials for their use in structural applications. While efforts in this regard are being carried out around the globe, the use of high strength eutectic alloys have, so far, received minor attention, although previous works showed that rapid solidification techniques can result in ultrafine microstructures with excellent mechanical performance, albeit for small sample sizes. In the present work, a eutectic Ti-32.5Fe alloy has been produced by laser powder bed fusion aiming at exploiting rapid solidification and the capability to produce bulk ultrafine microstructures provided by this processing technique. Process energy densities between 160 J/mm³ and 180 J/mm³ resulted in a dense and crack-free material with an oxygen content of ~ 0.45 wt.% in which a hierarchical microstructure is formed by µm-sized η-Ti4Fe2Ox dendrites embedded in an ultrafine eutectic β-Ti/TiFe matrix. The microstructure was studied three-dimensionally using near-field synchrotron ptychographic X-ray computed tomography with an actual spatial resolution down to 39 nm to analyse the morphology of the eutectic and dendritic structures as well as to quantify their mass density, size and distribution. Inter-lamellar spacings down to ~ 30–50 nm were achieved, revealing the potential of laser-based additive manufacturing to generate microstructures smaller than those obtained by classical rapid solidification techniques for bulk materials. The alloy was deformed at 600 °C under compressive loading up to a strain of ~ 30% without damage formation, resulting in a compressive yield stress of ~ 800 MPa. This study provides a first demonstration of the feasibility to produce eutectic Ti-Fe alloys with ultrafine microstructures by laser powder bed fusion that are suitable for structural applications at elevated temperature.

Authors 12

1. Joachim Gussone corresponding

   Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

   Affiliation as printed

   German Aerospace Center DLR, Institute of Materials Research, Linder Höhe, 51147 Cologne, Germany

2. Katrin Bugelnig

   Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

   Affiliation as printed

   German Aerospace Center DLR, Institute of Materials Research, Linder Höhe, 51147 Cologne, Germany

3. Pere Barriobero Vila

   Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

   Affiliation as printed

   German Aerospace Center DLR, Institute of Materials Research, Linder Höhe, 51147 Cologne, Germany

4. Júlio César da Silva

   Centre National de la Recherche Scientifique · European Synchrotron Radiation Facility · Institut Néel

   Affiliation as printed

   European Synchrotron Radiation Facility, 71, Avenue des Martyrs, 38043 Grenoble, France

   Institut Néel CNRS UPR2940, 25 Avenue des Martyrs BP 166, 38042 Grenoble, France

5. U. Hecht Aachen Access e.V

   Access

   Affiliation as printed

   Access e.V., Intzestr. 5, 52072 Aachen, Germany

6. Christian Dresbach

   Hochschule Bonn-Rhein-Sieg

   Affiliation as printed

   University of Applied Sciences Bonn-Rhein-Sieg, Von-Liebig Str. 20, 53359 Rheinbach, Germany

7. Federico Sket

   IMDEA Materials

   Affiliation as printed

   IMDEA Materiales, Eric Kandel 2, Tecnogetafe, 28906 Getafe, Madrid, Spain

8. Peter Cloetens

   European Synchrotron Radiation Facility

   Affiliation as printed

   European Synchrotron Radiation Facility, 71, Avenue des Martyrs, 38043 Grenoble, France

9. Andreas Stark

   Helmholtz-Zentrum Hereon

   Affiliation as printed

   Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany

10. Norbert Schell

    Helmholtz-Zentrum Hereon

    Affiliation as printed

    Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany

11. Jan Haubrich

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    German Aerospace Center DLR, Institute of Materials Research, Linder Höhe, 51147 Cologne, Germany

12. Guillermo Carlos Requena Aachen

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · RWTH Aachen University

    Affiliation as printed

    German Aerospace Center DLR, Institute of Materials Research, Linder Höhe, 51147 Cologne, Germany

    RWTH Aachen University, Metallic Structures and Materials Systems for Aerospace Engineering, D-52062 Aachen, Germany