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

Joachim Gussone (1) , Katrin Bugelnig (1) , Pere Barriobero-Vila (1) , Julio Cesar da Silva (2) , Ulrike Hecht (3) , Christian Dresbach (4) , Federico Sket (5) , Peter Cloetens (6) , Andreas Stark (7) , Norbert Schell (7) , Jan Haubrich (1) , Guillermo Requena (1)

1 DLR Institut für Werkstoff-Forschung / Institute of Materials Research
2 NEEL - MRS - Matériaux, Rayonnements, Structure
3 ACCESS (GERMANY)
4 H-BRS - Hochschule Bonn Rhein-Sieg University of Applied Sciences [Sankt Augustin]
5 Institute IMDEA Materials [Madrid]
6 ESRF - European Synchrotron Radiation Facility
7 GKSS - Helmholtz-Zentrum Geesthacht

High temperature laser powder bed fusion Eutectic Ti-Fe alloys Near-field synchrotron ptychographic X-ray computed tomography Ultrafine microstructures High temperature deformation a b s t r a c t 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 effort s 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/mm ³ and 180 J/mm ³ 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-Ti 4 Fe 2 O x 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 mi-crostructures 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 ultra-fine microstructures by laser powder bed fusion that are suitable for structural applications at elevated temperature.

Mots clés: High temperature laser powder bed fusion; Eutectic Ti-Fe alloys; Near-field synchrotron ptychographic X-ray computed tomography; Ultrafine microstructures; High temperature deformation

Domaines: Matériaux

Joachim Gussone, Katrin Bugelnig, Pere Barriobero-Vila, Julio Cesar da Silva, Ulrike Hecht, et al.. Ultrafine eutectic Ti-Fe-based alloys processed by additive manufacturing – A new candidate for high temperature applications. Applied Materials Today, 2020, 20, pp.100767. ⟨10.1016/j.apmt.2020.100767⟩. ⟨hal-02910772⟩