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@PHDTHESIS{Roth:1009108,
      author       = {Roth, Jan-Philipp},
      othercontributors = {Krupp, Ulrich and Jahns, Katrin and Kruml, Tomáš},
      title        = {{L}aser powder bed fusion of dispersion strengthened alloy
                      400},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2025-03342},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2025},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, Rheinisch-Westfälische Technische
                      Hochschule Aachen, 2025, Kumulative Dissertation},
      abstract     = {Additive manufacturing (AM) evolved rapidly during the last
                      decades. Other than conventional manufacturing (CM), this
                      technology allows for near-net-shape components, barely
                      being limited by geometrical constraints. Revealing very
                      fine grains, that, in turn, consist of cellular
                      nanostructures, the resulting performance of such components
                      differentiates significantly from CM. Continuous research is
                      thus required to fully understand this comparably young
                      manufacturing technology. Hence, the first pillar of this
                      work is considering the manufacturing. Besides AM, the
                      modification of base alloy systems via the concept of
                      dispersion strengthening (DS) has attracted great attention
                      in recent years. The implementation of nanoscaled ceramics
                      into the lattice of the alloy results in so-called metal
                      matrix nanocomposites (MMNC). This material class shows
                      clearly improved mechanical properties, mainly being linked
                      to the successful suppression of dislocation movements.
                      Being dependent on a complex multitude of factors, efficient
                      DS requires considerably more fundamental studies to
                      generate a complete picture. Therefore, this thesis also
                      deals with the mechanism.Thirdly, among the wide variety of
                      material classes used in high-performance industries,
                      NiCu-based alloys enable essential products like heat
                      exchangers, pumps, and valves in key sectors like maritime,
                      energy, and chemistry. A prominent representant of this
                      material category is Alloy 400. However, barely any
                      knowledge is available on this alloy when manufactured
                      additively, restricting its potential application.
                      Consequently, the material is covered in this thesis as
                      well. Combining these subject areas, this thesis establishes
                      holistic process routes for Laser Powder Bed Fusion of
                      Dispersion Strengthened Alloy 400 variants. It is documented
                      how to generate powder feedstocks for laser beam powder bed
                      fusion of metals (PBF-LB/M) via gas atomization of Alloy 400
                      and the peculiarities of powders and parts are disclosed.
                      Copper segregations on both grain boundaries and cell walls
                      such as high dislocation densities throughout the micro
                      dendritic structure were found. Due to the overall finer
                      grain structure of the AM variant, tensile properties
                      increased, and elongation lowered compared to CM. Based on
                      the findings of unmodified standard Alloy 400, two
                      successful DS modification routes were elaborated for the
                      present alloy. The first one is based on a gas atomization
                      reaction synthesis (GARS) principle. The feasibility of
                      nanoparticle formation in situ during atomization due to
                      reaction of the atomization gas with the melt was
                      demonstrated. The ceramics were identified as TiN and they
                      successfully limited dislocation movement throughout the
                      matrix via pinning. This resulted in considerably improved
                      mechanical properties compared to the standard PBF-LB/M
                      variant. The second modification approach applied an ex situ
                      powder modification in a fluidized bed reactor (FBR).
                      Enabled by nitrogen diffusion, a high number of TiN was
                      generated in powders which was again significantly increased
                      after AM, allowing for outstanding tensile, creep, and
                      fatigue performance.Therefore, several alloy systems have
                      been developed and qualified for use in AM while enabling
                      outstanding properties.},
      cin          = {522110 / 520000},
      ddc          = {620},
      cid          = {$I:(DE-82)522110_20180901$ / $I:(DE-82)520000_20140620$},
      pnm          = {topAM - Tailoring ODS materials processing routes for
                      additive manufacturing of high temperature devices for
                      aggressive environments (958192)},
      pid          = {G:(EU-Grant)958192},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2025-03342},
      url          = {https://publications.rwth-aachen.de/record/1009108},
}