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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.
    Müller, M.
    et al.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany; Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany.
    Labisch, C. C.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Gerdt, L.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Bach, L.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Riede, M.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Kaspar, J.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    López, Elena
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Brueckner, Frank
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany.
    Zimmermann, M.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany; Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany.
    Leyens, C.
    Fraunhofer IWS, Winterbergstraße 28, Dresden 01277, Germany; Technische Universität Dresden, Helmholtzstr. 7, 01069 Dresden, Germany.
    Multimaterial direct energy deposition: From three-dimensionally graded components to rapid alloy development for advanced materials2023Ingår i: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 35, nr 1, artikel-id 012006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser-based direct energy deposition (L-DED) with blown powder enables the simultaneous or sequential processing of different powder materials within one component and, thus, offers the possibility of additive multimaterial manufacturing. Therefore, the process allows a spatially resolved material allocation and fabrication of sharp or even graded material transitions. Within this contribution, the latest results from two major research fields in multimaterial L-DED—(I) automation and (II) rapid alloy development of high entropy alloys (HEAs) by in situ synthesis—shall be presented. First, an automated multimaterial deposition process was developed, which enables the automated manufacturing of three-dimensionally graded specimens. For this, a characterization of the deposition system regarding powder feeding dynamics and resulting powder mixtures in the process zone was conducted. The obtained system characteristics were used to achieve a three-dimensional deposition of specified powder mixtures. The fabricated specimens were analyzed by energy-dispersive x-ray spectroscopy, scanning electron microscopy, and micro hardness measurement. The research demonstrates the increasing readiness of L-DED for the fabrication of multimaterial components. Second, the latest results from rapid alloy development for HEAs by DED are presented. By the simultaneous usage of up to four powder feeders, a vast range of alloy compositions within the Al–Ti–Co–Cr–Fe–Ni HEA system was investigated. For this, tailored measurement systems such as an in-house developed powder sensor were beneficially used. The study shows the influence of a variation of Al on the phase formation and resulting mechanical properties and demonstrates the potential of L-DED for reducing development times for new alloys.

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  • 3.
    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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