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  • 1.
    Gruber, Samira
    et al.
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Gerdt, Leonid
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Lopez, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Kieser, Jan
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany; TUD Dresden University of Technology, Institute of Materials Science, 01069, Dresden, Germany.
    Bratt, Craig
    Fraunhofer USA—Center Midwest, Laser Applications Division, Plymouth, Michigan 48170, United States.
    Process development for laser powder bed fusion of GRCop-42 using a 515 nm laser source2023Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 35, nr 4, artikel-id 042078Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Copper is widely used in high heat flux and electrical applications because of its excellent electrical and thermal conductivity properties. Alloying elements such as chromium or nickel are added to strengthen the material, especially for higher temperatures. Cu4Cr2Nb, also known as GRCop-42, is a dispersion-strengthened copper-chromium-niobium alloy developed by NASA for high-temperature applications with high thermal and mechanical stresses such as rocket engines. Additive manufacturing (AM) enables applications with complex functionalized geometries and is particularly promising in the aerospace industry. In this contribution, a parametric study was performed for GRCop-42 and the AM process laser powder bed fusion (PBF-LB/M) using a green laser source for two-layer thicknesses of 30 and 60 µm. Density, electrical conductivity, hardness, microstructure, and static mechanical properties were analyzed. Various heat treatments ranging from 400 to 1000 °C and 30 min to 4 h were tested to increase the electrical conductivity and hardness. For both layer thicknesses, dense parameter sets could be obtained with resulting relative densities above 99.8%. Hardness and electrical conductivity could be tailored in the range of 103-219 HV2 and 24%-88% International Annealed Copper Standard (IACS) depending on the heat treatment. The highest ultimate tensile strength (UTS) obtained was 493 MPa. An aging temperature of 700 °C for 30 min showed the best combination of room temperature properties such as electrical conductivity of 83.76%IACS, UTS of 481 MPa, elongation at break (A) at 24%, and hardness of 125 HV2.

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  • 2.
    Moritz, Juliane
    et al.
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Teschke, Mirko
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Marquardt, Axel
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Heinze, Stefan
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany.
    Heckert, Mirko
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany.
    Stepien, Lukas
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    López, Elena
    Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Walther, Frank
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Leyens, Christoph
    Technische Universität Dresden, Institute of Materials Science (IfWW), 01069, Dresden, Germany; Technology Field Additive Manufacturing and Surface Technologies, Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Influence of Two-Step Heat Treatments on Microstructure and Mechanical Properties of a β-Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion2023Ingår i: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, nr 2, artikel-id 2200931Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Additive manufacturing technologies, particularly electron beam powder bed fusion (PBF-EB/M), are becoming increasingly important for the processing of intermetallic titanium aluminides. This study presents the effects of hot isostatic pressing (HIP) and subsequent two-step heat treatments on the microstructure and mechanical properties of the TNM-B1 alloy (Ti–43.5Al–4Nb–1Mo–0.1B) fabricated via PBF-EB/M. Adequate solution heat treatment temperatures allow the adjustment of fully lamellar (FL) and nearly lamellar (NL-β) microstructures. The specimens are characterized by optical microscopy and scanning electron microscopy (SEM), X-ray computed tomography (CT), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical properties at ambient temperatures are evaluated via tensile testing and subsequent fractography. While lack-of-fusion defects are the main causes of failure in the as-built condition, the mechanical properties in the heat-treated conditions are predominantly controlled by the microstructure. The highest ultimate tensile strength is achieved after HIP due to the elimination of lack-of-fusion defects. The results reveal challenges originating from the PBF-EB/M process, for example, local variations in chemical composition due to aluminum evaporation, which in turn affect the microstructures after heat treatment. For designing suitable heat treatment strategies, particular attention should therefore be paid to the microstructural characteristics associated with additive manufacturing.

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  • 3.
    Moritz, Juliane
    et al.
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Teschke, Mirko
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Marquardt, Axel
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    López, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany.
    Walther, Frank
    Chair of Materials Test Engineering (WPT), TU Dortmund University, 44227, Dortmund, Germany.
    Leyens, Christoph
    Institute of Materials Science (IfWW), Technische Universität Dresden, 01069, Dresden, Germany; Fraunhofer Institute for Material and Beam Technology IWS, 01277, Dresden, Germany.
    Influence of Electron Beam Powder Bed Fusion Process Parameters at Constant Volumetric Energy Density on Surface Topography and Microstructural Homogeneity of a Titanium Aluminide Alloy2023Ingår i: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, nr 15, artikel-id 2201871Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In powder bed fusion additive manufacturing, the volumetric energy density E V is a commonly used parameter to quantify process energy input. However, recent results question the suitability of E V as a design parameter, as varying the contributing parameters may yield different part properties. Herein, beam current, scan velocity, and line offset in electron beam powder bed fusion (PBF-EB) of the titanium aluminide alloy TNM–B1 are systematically varied while maintaining an overall constant E V. The samples are evaluated regarding surface morphology, relative density, microstructure, hardness, and aluminum loss due to evaporation. Moreover, the specimens are subjected to two different heat treatments to obtain fully lamellar (FL) and nearly lamellar (NLγ) microstructures, respectively. With a combination of low beam currents, low-to-intermediate scan velocities, and low line offsets, parts with even surfaces, relative densities above 99.9%, and homogeneous microstructures are achieved. On the other hand, especially high beam currents promote the formation of surface bulges and pronounced aluminum evaporation, resulting in inhomogeneous banded microstructures after heat treatment. The results demonstrate the importance of considering the individual parameters instead of E V in process optimization for PBF-EB.

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  • 4.
    Müller, Michael
    et al.
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Enghardt, Stefan
    Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Kuczyk, Martin
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Riede, Mirko
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    López, Elena
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    Marquardt, Axel
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Leyens, Christoph
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Microstructure of NiAl-Ta-Cr in situ alloyed by induction-assisted laser-based directed energy deposition2024Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 238, artikel-id 112667Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of new high temperature materials for coatings as well as structural components is an important topic to contribute to a higher efficiency and sustainability of e.g. gas turbine engines. One promising new class of high temperature materials are NiAl-based alloys. Within this study, the microstructure and microhardness of NiAl-Ta-Cr alloys with varying Cr and Ta content were investigated. Graded specimens were fabricated by laser-based directed energy deposition utilizing an in situ alloying approach by mixing elemental Ta and Cr as well as pre-alloyed NiAl powder. Thermodynamic calculations were performed to design the alloy compositions beforehand. Inductive preheating of the substrate was used to counter the challenge of cracking due to the high brittleness. The results show that the cracking decreases with increasing preheating temperature. However, even at 700 °C, the cracking cannot be fully eliminated. Scanning electron microscopy, X-ray diffraction and electron backscatter diffraction revealed the formation of the phases B2-NiAl, A2-Cr and C14-NiAlTa within NiAl-Ta and NiAl-Cr alloys. For NiAl-Ta-Cr compositions, deviations regarding the phase formation between calculation and experiment were observed. Maximum hardness values were achieved within the NiAl-Ta and NiAl-Ta-Cr systems for the eutectic compositions at 14 at.-% Ta with maximum values above 900 HV0.1.

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  • 5.
    Selbmann, Alex
    et al.
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Gruber, Samira
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Propst, Martin
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Dorau, Tim
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Drexler, Robert
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Toma, Filofteia-Laura
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Mueller, Michael
    Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Stepien, Lukas
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Lopez, Elena
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Bach, Christian
    Institute of Aerospace Engineering, TUD Dresden University of Technology, Dresden 01602, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany.
    Leyens, Christoph
    Fraunhofer Institute for Material and Beam Technology IWS, Dresden 01277, Germany; Institute of Materials Science, TUD Dresden University of Technology, Dresden 01069, Germany.
    Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine2024Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 36, nr 1, artikel-id 012027Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints.

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  • 6.
    Sheydaeian, Esmat
    et al.
    University of Toronto, Toronto, Canada.
    Gerdt, Leonid
    Fraunhofer IWS, Dresden, Germany.
    Stepien, Lukas
    Fraunhofer IWS, Dresden, Germany.
    Lopez, Elena
    Fraunhofer IWS, Dresden, Germany.
    Brückner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Dresden, Germany.
    Leyens, Christoph
    Fraunhofer IWS, Dresden, Germany; Dresden University of Technology, Germany.
    PBF-LB of zinc composites modified with nanopowders: Initial insights into powder and part characterizations2024Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 361, artikel-id 136076Artikel i tidskrift (Refereegranskat)
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