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Brückner, Frank
Alternative names
Publications (10 of 67) Show all publications
Brandau, B., Brueckner, F. & Kaplan, A. F. H. (2024). Absorbance determination of a powder bed by high resolution coaxial multispectral imaging in laser powder bed fusion. Optics and Laser Technology, 168, Article ID 109780.
Open this publication in new window or tab >>Absorbance determination of a powder bed by high resolution coaxial multispectral imaging in laser powder bed fusion
2024 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 168, article id 109780Article in journal (Refereed) Published
Abstract [en]

This study presents an approach for in-situ monitoring of laser powder bed fusion. Using standard laser optics, coaxial high-resolution multispectral images of powder beds are acquired in a pre-objective scanning configuration. A continuous overview image of the entire 114 × 114 mm powder bed can be generated, detecting objects down to 20 µm in diameter with a maximum offset of 22–49 µm. Multispectral information is obtained by capturing images at 6 different wavelengths from 405 nm to 850 nm. This allows in-line determination of the absorbance of the powder bed with a maximum deviation of 2.5% compared to the absorbance spectra of established methods. For the qualification of this method, ray tracing simulations on powder surfaces and tests with 20 different powders have been carried out. These included different particle sizes, aged and oxidized powders.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Spectroscopic Measurement, Correction Method, Laser Powder Bed Fusion, Scanning Method, Metal Powder, Multispectral Imaging, Laser Material Processing
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-99249 (URN)10.1016/j.optlastec.2023.109780 (DOI)2-s2.0-85166468238 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-08-07 (hanlid)

Available from: 2023-08-02 Created: 2023-08-02 Last updated: 2023-11-17Bibliographically approved
Müller, M., Enghardt, S., Kuczyk, M., Riede, M., López, E., Brueckner, F., . . . Leyens, C. (2024). Microstructure of NiAl-Ta-Cr in situ alloyed by induction-assisted laser-based directed energy deposition. Materials & design, 238, Article ID 112667.
Open this publication in new window or tab >>Microstructure of NiAl-Ta-Cr in situ alloyed by induction-assisted laser-based directed energy deposition
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2024 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 238, article id 112667Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
Keywords
Additive manufacturing, Advanced materials, Direct energy deposition, In situ alloying, Intermetallics, Nickel aluminide
National Category
Metallurgy and Metallic Materials Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-104289 (URN)10.1016/j.matdes.2024.112667 (DOI)2-s2.0-85183602891 (Scopus ID)
Note

Funder: DFG (457729030); Array (457729030);

Full text license: CC BY-NC-ND

Available from: 2024-02-15 Created: 2024-02-15 Last updated: 2024-02-15
Sheydaeian, E., Gerdt, L., Stepien, L., Lopez, E., Brückner, F. & Leyens, C. (2024). PBF-LB of zinc composites modified with nanopowders: Initial insights into powder and part characterizations. Materials letters (General ed.), 361, Article ID 136076.
Open this publication in new window or tab >>PBF-LB of zinc composites modified with nanopowders: Initial insights into powder and part characterizations
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2024 (English)In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 361, article id 136076Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-104346 (URN)10.1016/j.matlet.2024.136076 (DOI)2-s2.0-85183962530 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-22 (signyg);

Funder: Alexander von Humboldt Stiftung; High-Performance Center of Fraunhofer-Gesellschaft

Available from: 2024-02-22 Created: 2024-02-22 Last updated: 2024-02-22Bibliographically approved
Selbmann, A., Gruber, S., Propst, M., Dorau, T., Drexler, R., Toma, F.-L., . . . Leyens, C. (2024). Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine. Journal of laser applications, 36(1), Article ID 012027.
Open this publication in new window or tab >>Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine
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2024 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 36, no 1, article id 012027Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Laser Institute of America, 2024
Keywords
additive manufacturing, aerospace, aerospike engine, laser powder bed fusion, nickel-based superalloys
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-104177 (URN)10.2351/7.0001121 (DOI)2-s2.0-85183453067 (Scopus ID)
Note

Funder: ESA (4000130551/20/NL/MG);

Full text license: CC BY

Available from: 2024-02-05 Created: 2024-02-05 Last updated: 2024-02-05
Schneider, J., Norman, A., Gumpinger, J., Brückner, F., Bavdaz, M., Leyens, C. & Ghidini, T. (2023). Additive manufacturing of a metallic optical bench—process development, material qualification and demonstration. CEAS Space Journal, 15(1), 55-68
Open this publication in new window or tab >>Additive manufacturing of a metallic optical bench—process development, material qualification and demonstration
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2023 (English)In: CEAS Space Journal, ISSN 1868-2502, E-ISSN 1868-2510, Vol. 15, no 1, p. 55-68Article in journal (Refereed) Published
Abstract [en]

With the large-class science mission ATHENA, the European Space Agency (ESA) aims at exploring the hot and energetic universe with advanced X-Ray technology. As a central component of the telescope, hundreds of silicon pore optic (SPO) modules will be assembled in an optical bench with a diameter of about 2.5 m. Several approaches are under investigation for the manufacturing of this supporting structure, and for handling the challenging constraints with respect to size, geometry and material. In cooperation with ESA, the Fraunhofer IWS is currently investigating the manufacturing of the optical bench made from Ti-6Al-4 V by means of Additive Manufacturing using Laser Metal Deposition (LMD) followed by subtractive finishing. Several development steps have been covered in a holistic manner starting with the system engineering of the production site. The main focus of the activity was on the process development for the Additive Manufacturing as well as the subtractive finishing. Furthermore, the properties of the produced material were also investigated. Within the scope of this publication, a general overview is given about the project related developments, achievements, and flanking activities for solving various challenges. The suitability of the developed technologies and workflows are now being evaluated through the manufacture of a representative, large-scale breadboard.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Additive manufacturing, Advanced manufacturing, DED-LB, Laser metal deposition, Ti-6Al-4 V
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-89453 (URN)10.1007/s12567-021-00409-w (DOI)000742808100001 ()2-s2.0-85123197738 (Scopus ID)
Funder
The European Space Agency (ESA), AO/1-8607/16/NL/LvH
Note

Validerad;2023;Nivå 2;2023-04-20 (hanlid)

Available from: 2022-03-07 Created: 2022-03-07 Last updated: 2023-04-20Bibliographically approved
Heidowitzsch, M., Gerdt, L., Samuel, C., Maetje, J.-F., Kaspar, J., Riede, M., . . . Leyens, C. (2023). Grain size manipulation by wire laser direct energy deposition of 316L with ultrasonic assistance. Paper presented at 42nd International Congress on Applications of Lasers & Electro-Optics (ICALEO), Chicago, Illinois, October 16-19, 2023. Journal of laser applications, 35(3), Article ID 032017.
Open this publication in new window or tab >>Grain size manipulation by wire laser direct energy deposition of 316L with ultrasonic assistance
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2023 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 35, no 3, article id 032017Article in journal (Refereed) Published
Abstract [en]

The epitaxial growth of coarse and columnar grain structures along the build direction of additive manufactured metals is a usual phenomenon. As a result, as-built components often exhibit pronounced anisotropic mechanical properties, reduced ductility, and, hence, a high cracking susceptibility. To enhance the mechanical properties and processability of additive manufactured parts, the formation of equiaxed and fine grained structures is thought to be most beneficial. In this study, the potential of grain refinement by ultrasonic excitation of the melt pool during laser wire additive manufacturing has been investigated. An ultrasound system was developed and integrated in a laser wire deposition machine. AISI 316L steel was used as a substrate and feedstock material. A conversion of coarse, columnar grains (d(m) = 284.5 mu m) into fine, equiaxed grains (d(m) = 130.4 mu m) and a weakening of typical -fiber texture with increasing amplitude were verified by means of light microscopy, scanning electron microscopy, and electron backscatter diffraction analysis. It was demonstrated that the degree of grain refinement could be controlled by the regulation of ultrasound amplitude. No significant changes in the dendritic structure have been observed. The combination of sonotrode/melt pool direct coupling and the laser wire deposition process represents a pioneering approach and promising strategy to investigate the influence of ultrasound on grain refinement and microstructural tailoring.

Place, publisher, year, edition, pages
AIP Publishing, 2023
Keywords
laser wire additive manufacturing, ultrasonic engineering, grain refinement, microstructure tailoring, crystallographic texture
National Category
Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-101207 (URN)10.2351/7.0001090 (DOI)001052650400001 ()
Conference
42nd International Congress on Applications of Lasers & Electro-Optics (ICALEO), Chicago, Illinois, October 16-19, 2023
Note

Godkänd;2023;Nivå 0;2023-09-05 (hanlid);Konferensartikel i tidskrift

Available from: 2023-09-05 Created: 2023-09-05 Last updated: 2023-09-05Bibliographically approved
Moritz, J., Teschke, M., Marquardt, A., Stepien, L., López, E., Brueckner, F., . . . Leyens, C. (2023). Influence of Electron Beam Powder Bed Fusion Process Parameters at Constant Volumetric Energy Density on Surface Topography and Microstructural Homogeneity of a Titanium Aluminide Alloy. Advanced Engineering Materials, 25(15), Article ID 2201871.
Open this publication in new window or tab >>Influence of Electron Beam Powder Bed Fusion Process Parameters at Constant Volumetric Energy Density on Surface Topography and Microstructural Homogeneity of a Titanium Aluminide Alloy
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2023 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, no 15, article id 2201871Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
additive manufacturing, aluminum evaporation, electron beam powder bed fusion, heat treatments, process parameters, titanium aluminides
National Category
Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-97281 (URN)10.1002/adem.202201871 (DOI)000976798900001 ()2-s2.0-85151432356 (Scopus ID)
Note

Godkänd;2023;Nivå 0;2023-08-15 (marisr);Konferensartikel i tidskrift

Special Issue: Structural Materials;

Funder: Deutsche Forschungsgemeinschaft, DFG (404665753, 406109547);

License fulltext: CC-BY. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Available from: 2023-05-23 Created: 2023-05-23 Last updated: 2023-08-15Bibliographically approved
Mueller, M., Franz, K., Riede, M., López, E., Brueckner, F. & Leyens, C. (2023). Influence of process parameter variation on the microstructure of thin walls made of Inconel 718 deposited via laser-based directed energy deposition with blown powder. Journal of Materials Science, 58(27), 11310-11326
Open this publication in new window or tab >>Influence of process parameter variation on the microstructure of thin walls made of Inconel 718 deposited via laser-based directed energy deposition with blown powder
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2023 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 58, no 27, p. 11310-11326Article in journal (Refereed) Published
Abstract [en]

In laser-based directed energy deposition (L-DED) of Inconel 718 the microstructure of the fabricated components strongly depends on the applied process parameters and the resulting solidification conditions. Numerous studies have shown that the process parameters deposition speed and laser power have a major influences on microstructural properties, such as dendrite morphology and segregation behavior. This study investigates how changes in these process parameters affect the microstructure and hardness when the line mass, and thus the resulting layer height, are kept constant. This enables the microstructural comparison of geometrically similar specimens that were manufactured with the same number of layers but severely different process parameters. This approach yields the benefit of almost identical geometrical boundary conditions, such as the layer-specific build-height and heat conducting cross section, for all specimens. For microstructural analysis scanning electron microscopy and energy dispersive X-ray spectroscopy were applied and the results evaluated in a quantitative manner. The microstructural features primary dendritic arm spacing, fraction and morphology of precipitated Laves phase as well as the spatially resolved chemical composition were measured along the build-up direction. The occurring cooling rates were calculated based on the primary dendritic arm spacing using semi-empirical models. Three different models used by others researchers were applied and evaluated with respect to their applicability for L-DED. Finally, microhardness measurements were performed for a baseline evaluation of the influence on the materials’ mechanical properties.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-99419 (URN)10.1007/s10853-023-08706-x (DOI)2-s2.0-85164202693 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-08-10 (hanlid)

Available from: 2023-08-10 Created: 2023-08-10 Last updated: 2023-08-10Bibliographically approved
Moritz, J., Teschke, M., Marquardt, A., Heinze, S., Heckert, M., Stepien, L., . . . Leyens, C. (2023). Influence of Two-Step Heat Treatments on Microstructure and Mechanical Properties of a β-Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion. Advanced Engineering Materials, 25(2), Article ID 2200931.
Open this publication in new window or tab >>Influence of Two-Step Heat Treatments on Microstructure and Mechanical Properties of a β-Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion
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2023 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 25, no 2, article id 2200931Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
additive manufacturing, electron beam powder bed fusion, mechanical characterizations, microstructural characterizations, titanium aluminides, two-step heat treatments
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-93793 (URN)10.1002/adem.202200931 (DOI)000870839300001 ()2-s2.0-85140393251 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-04-19 (hanlid);

Funder: German Research Foundation (DFG) (404665753, 40610954)

Available from: 2022-11-03 Created: 2022-11-03 Last updated: 2023-04-24Bibliographically approved
Kaplan, A. F. H., Fedina, T., Brückner, F. & Powell, J. (2023). Laser induced reduction of iron ore by silicon. Journal of Alloys and Metallurgical Systems, 4, Article ID 100039.
Open this publication in new window or tab >>Laser induced reduction of iron ore by silicon
2023 (English)In: Journal of Alloys and Metallurgical Systems, ISSN 2949-9178, Vol. 4, article id 100039Article in journal (Refereed) Published
Abstract [en]

Iron ore powder accompanied by Si-powder as a reducing agent, was melted using a high-power laser beam. During laser melting of the two different powder beds placed next to each other, silicon merged and diffused into the iron ore, forming a ternary melt phase Fe-O-Si of around 30–60–10 at%. High speed imaging of the laser melting process as well as subsequent SEM-analysis of the generated nuggets showed the formation of droplets that merge with the surrounding Si- or ore-powder and form distinct domains. Under certain circumstances, the solidifying nuggets, of the order of 0.5–5 mm in size, generated numerous small domains, up to 25 µm, of high purity iron, 90 + at%, surrounded by a matrix of the above mentioned slag. Many of these Fe-domains were created in the vicinity of regions of high Si-content.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Laser treatment, Reduction, Iron, Iron ore, Powder processing, Ore reduction, Silicon
National Category
Other Materials Engineering Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-102647 (URN)10.1016/j.jalmes.2023.100039 (DOI)
Funder
Swedish Energy Agency, 51021-1, P2022-00202
Note

Godkänd;2023;Nivå 0;2023-11-22 (joosat);

CC BY 4.0 License

Funder: EU ERDF Kolarctic CBC with Region Norrbotten, project I2P, (no. KO4012); LKAB

Available from: 2023-11-22 Created: 2023-11-22 Last updated: 2023-11-22Bibliographically approved
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