@misc{SchmidtEmdadiHaertel, author = {Schmidt, Alexander and Emdadi, Aliakbar and H{\"a}rtel, Sebastian}, title = {A holistic approach for near-net-shape processing of iron aluminides by means of Laser Directed Energy Deposition with cored wires}, series = {77th IIW Annual assembly and international conference on welding and joining, 7-12 July 2024, Rhodes}, volume = {2024}, journal = {77th IIW Annual assembly and international conference on welding and joining, 7-12 July 2024, Rhodes}, pages = {6}, abstract = {Iron aluminides are characterized by high corrosion resistance, excellent mechanical properties and dimensional stability at high temperatures. With a low density this material offers technological and economic advantages over Ni-based alloys in the aerospace sector. Because of the excellent mechanical properties machining is the current challenge in processing Fe-Al. Due to the possibility of near-net-shape manufacturing along with high material efficiency additive manufacturing processes such as L-DED with wires seem to be predestined for the processing of Fe-Al. In this paper, a holistic approach for processing Fe-Al including manufacturing of wires and the actual processing of the wires is described. Since the wire drawing of iron aluminides is not possible due to low forming characteristics, a rotary swaging process was applied for manufacturing cored wires with a steel shell and aluminum core. On the one hand, the usage of unalloyed raw materials with suitable forming properties are advantageous. On the other hand, cored wires require in-situ alloying of the steel shell and aluminum core during the application process. Thus, the weldability of such cored wires was investigated in preliminary tests, initially using a tungsten inert gas welding process. The wires and the welding results were characterized by scanning electron microscopy, hardness measurement, and X-ray analyses.}, language = {en} } @misc{EmdadiJenschSzyndleretal., author = {Emdadi, Aliakbar and Jensch, Felix and Szyndler, Joanna and Huang, Hsuan-Po and H{\"a}rtel, Sebastian and Weiß, Sabine}, title = {Void closure behavior during hot forming of an Fe-Al alloy}, series = {Materials research proceedings}, volume = {54}, journal = {Materials research proceedings}, publisher = {IWA Publishing}, address = {Millersville, PA}, isbn = {978-1-64490-359-9}, issn = {2474-395X}, doi = {10.21741/9781644903599-99}, pages = {927 -- 935}, abstract = {Hot forging is a forming process that can be used as a post-processing treatment to close residual porosity and refine the microstructure of additively manufactured materials, resulting in improved mechanical properties. During hot forging, void closure occurs through plastic deformation resulting from a predominantly compressive stress state at elevated temperatures. In the present work, Fe-25Al-1.5Ta (at. \%) samples have been produced by laser powder bed fusion (LPBF) using a larger layer thickness and scan speed than commonly used to achieve a target porosity fraction of approximately 10\%. Full densification is attempted in the subsequent hot compression step at various height reduction ratios. The as-built LPBF samples contained 8-10\% voids. After deformation to true strains of 0.2, 0.4, and 0.6, the void fraction decreased significantly to approximately 4\%, 2.3\%, and 1.1\%, respectively. Hot compression resulted in the complete closure of large pores with a size range of 200-300 µm and a significant reduction in the size of small to medium pores. These results show potential for improving the productivity of the LPBF by speeding up the process by increasing layer thickness and scanning speed while maintaining a reasonable density. Full densification should be achieved by subsequent hot forging.}, language = {en} } @misc{ErtugrulEmdadiJedynaketal., author = {Ertugrul, G{\"o}khan and Emdadi, Aliakbar and Jedynak, Angelika and Weiß, Sabine and H{\"a}rtel, Sebastian}, title = {Hot forming behavior of tungsten carbide reinforced Ni-based superalloy 625 additively manufactured by laser directed energy deposition}, series = {Additive manufacturing letters}, volume = {13}, journal = {Additive manufacturing letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2772-3690}, doi = {10.1016/j.addlet.2025.100267}, pages = {1 -- 12}, abstract = {The demands of high-performance industries such as aerospace, automotive, tool manufacturing, oil, and gas industries are driving the innovation in high-performance materials and their production methods. This study explores the impact of hybrid manufacturing, specifically the effect of the addition of tungsten carbide (WC/W2C) via Laser-Directed Energy Deposition (L-DED), on the hot workability, hardness, and microstructure of nickel-based superalloy Inconel 625 (IN625). IN625 is known for its high temperature and high corrosion resistance, and tungsten carbide for its high wear resistance and grain refinement effect. The integration of WC/W2C particles into the IN625 matrix, in addition to the use of the hybrid approach of additive manufacturing followed by a hot-forming process, significantly influences the microstructure and mechanical behavior of the material. Thus, while incorporation of the WC/W2C can strengthen the material and extend the mechanical limitations, its full impact, including any potential usages, should be thoroughly evaluated for the intended application of the materials. To understand the effect of WC/W2C, additive manufacturing of IN625 both with and without WC/W2C and isothermal hot compression was carried out. The objective is to analyze the differences in microstructure and properties between L-DED manufactured IN625, and WC-reinforced IN625, and their hot-forming behavior, focusing on the effects of WC addition and post-deformation on microstructure and mechanical properties. This work represents the first investigation into the effect of WC/W2C hard particles on the hot-forming process of additively manufactured Ni-based metal matrix composites.}, language = {en} } @misc{ErtugrulEmdadiHaertel, author = {Ertugrul, G{\"o}khan and Emdadi, Aliakbar and H{\"a}rtel, Sebastian}, title = {Powder production and additive manufacturing of iron aluminide alloys using plasma ultrasonic atomization and laser-directed energy deposition}, series = {Additive manufacturing letters}, volume = {14}, journal = {Additive manufacturing letters}, editor = {MacDonald, Eric W.}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2772-3690}, doi = {10.1016/j.addlet.2025.100313}, pages = {1 -- 9}, abstract = {With a combination of desirable properties such as low density, high specific yield strength, low material cost, and excellent oxidation and corrosion resistance, iron aluminide (Fe-Al) has shown considerable potential to be an alternative to high-alloy chromium steels, and in some cases even nickel-based superalloys, in high-temperature applications. Due to these features, it is especially suitable for the aerospace and automotive industries. Recent advancements indicate an increasing interest in Fe-Al within the additive manufacturing industry, particularly in directed energy deposition (DED) processes. Despite this progress, processing of Fe-Al materials using the laser directed energy deposition (L-DED) has not been sufficiently investigated. In this study, Fe-Al powder material was produced from a commercial Al rod encased in a commercial low alloy-steel tube by a plasma-based ultrasonic atomization eliminating the need to cast an alloy ingot in advance. Subsequently, the produced powder was used in a l-DED process to fabricate an additively manufactured sample. The sample was investigated in terms of mechanical property, microstructure, chemical composition, and phase structure by scanning electron microscope (SEM) / energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and microhardness analyses.}, language = {en} } @misc{ErtugrulEmdadiHaertel, author = {Ertugrul, G{\"o}khan and Emdadi, Aliakbar and H{\"a}rtel, Sebastian}, title = {Advancements in iron aluminide alloy processing : a comparative study with DED alternatives}, series = {Materials research proceedings}, volume = {54}, journal = {Materials research proceedings}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, issn = {2474-395X}, doi = {10.21741/9781644903599-28}, pages = {254 -- 263}, abstract = {This article investigates the processing and characterization of iron aluminide lightweight alloy by plasma ultrasonic atomization and laser powder based directed energy deposition (DED-LB/p) and its comparison with other additive manufacturing alternatives. DED-LB/p provides precisely controllable process parameters, a wide range of feed materials supplied in powder form, a relatively high deposition rate and low heat input. These features favor the DED - LB/p process for novel materials such as iron aluminide. Thanks to a combination of desirable properties such as low density, high specific strength, low material cost, excellent oxidation resistance, and corrosion resistance, Fe-Al has established considerable potential to replace high-alloy chromium steels and, in some cases, even superalloys in high-temperature applications. In this study, Fe-Al alloy was first atomized into powder form from a commercial rod with core of aluminum and sleeve of a commercial low alloy-steel by plasma ultrasonic atomization. The resulting powder was then used for additive manufacturing with DED-LB/p in order to reduce cost and analyze the process chain. The results show that the use of powder produced by plasma ultrasonic atomization from commercial raw materials in the DED-LB/p process provides an effective combination for additive manufacturing of Fe-Al alloy and has some advantages over the alternative WAAM method.}, language = {en} } @misc{EmdadiYangSzyndleretal., author = {Emdadi, Aliakbar and Yang, Yitong and Szyndler, Joanna and Jensch, Felix and Ertugrul, G{\"o}khan and Tovar, Michael and H{\"a}rtel, Sebastian and Weiß, Sabine}, title = {Highly printable Fe₃Al intermetallic alloy}, series = {Metals : open access journal}, volume = {16}, journal = {Metals : open access journal}, number = {5}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/met16010005}, pages = {1 -- 15}, abstract = {Intermetallic Fe₃Al-based alloys reinforced with Laves-phase precipitates are emerging as potential replacements for conventional high-alloy steels and possibly polycrystalline Ni-based superalloys in structural applications up to 700 °C. Their impressive mechanical properties, however, are offset by limited fabricability and poor machinability due to their severe brittleness. High tool wear during finish-machining, which is still required for components such as turbine blades, remains a key barrier to their broader adoption. In contrast to conventional manufacturing routes, additive manufacturing offers a viable solution by enabling near-net-shape manufacturing of difficult-to-machine iron aluminides. In the present study, laser powder bed fusion was used to produce an Fe-25Al-1.5Ta intermetallic containing strengthening Laves-phase precipitates, and the porosity, microstructure and phase composition were characterized as a function of the process parameters. The results showed that preheating the build plate to 650 °C effectively suppressed delamination and macrocrack formation, even though noticeable cracking still occurred at the high scan speed of 1000 mm/s. X-ray tomography revealed that samples fabricated with a lower scan speed (500 mm/s) and a higher layer thickness (0.1 mm) contained larger, irregularly shaped pores, whereas specimens printed at the same volumetric energy density (40 J/mm3) but with different parameter sets exhibited smaller fractions of predominantly spherical pores. All samples contained mostly elongated grains that were either oriented close to <001> relative to the build direction or largely texture-free. X-ray diffraction confirmed the presence of Fe₃Al and C14-type (Fe, Al)₂Ta Laves phase in all samples. Hardness values fell within a narrow range (378-398 HV10), with only a slight reduction in the specimen exhibiting higher porosity.}, language = {en} }