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@PHDTHESIS{vonLintel:1017256,
      author       = {von Lintel, Heinrich},
      othercontributors = {Krupp, Ulrich and Jahns, Katrin},
      title        = {{E}ntwicklung ausscheidungshärtbarer {K}upferlegierungen
                      für die additive {F}ertigung von
                      {H}ochleistungs-{E}lektronikbauteilen},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2025-07248},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2025},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, Rheinisch-Westfälische Technische
                      Hochschule Aachen, 2025},
      abstract     = {Additive powder bed fusion processes play an increasingly
                      important role in industrial applications. The processing of
                      highly reflective metals such as the copper alloy CuCr1Zr is
                      a focal point of current research. CuCr1Zr is characterized
                      by high electrical conductivity combined with excellent
                      mechanical strength. The additive manufacturing of CuCr1Zr
                      offers new application opportunities thanks to its design
                      freedom and flexibility in material customization. However,
                      the high thermal conductivity and low absorptivity of
                      CuCr1Zr present challenges for the manufacturing process.
                      Previous research has primarily focused on optimizing
                      manufacturing parameters for the well-established Laser
                      Powder Bed Fusion (PBF-LB/M) with a red laser, and on
                      analyzing the mechanical and electrical properties of
                      CuCr1Zr. In contrast, aspects such as the oxidation behavior
                      of the powder have often been overlooked. This study
                      therefore includes comprehensive investigations into the
                      powder production and the oxidation behavior of CuCr1Zr.
                      Furthermore, the processing of the powder using PBF-LB/M
                      with a green laser source is examined and, the tailoring of
                      material properties through targeted alloy design is
                      addressed. Metal powders for additive manufacturing are
                      typically produced via gas atomization. In this context, the
                      atomization of a CuCr1Zr molten jet was analyzed using
                      high-speed imaging to calculate the conditions for secondary
                      atomization as a function of gas pressure. Calorimetric
                      measurements and isothermal oxidation experiments revealed
                      that initial signs of oxidation appear after 42 days in a
                      nitrogen atmosphere at room temperature. The oxide growth
                      follows a logarithmic trend, characterized by the formation
                      and transformation of Cu2O to CuO.A promising approach to
                      improving the processability of copper and its alloys in
                      additive manufacturing involves using a green laser with a
                      wavelength of 530 nm. In this study, suitable processing
                      parameters for PBF-LB/M of CuCr1Zr with a green
                      quasi-continuous wave laser (QCW laser) were determined
                      through design of experiments. A maximum relative density of
                      99,6 $\%$ was achieved at a laser power of 125 W, a scanning
                      speed of 400 mm/s, and a hatching distance of 100 µm. The
                      study demonstrated a strong dependence of relative density
                      on laser power and hatching distance. By leveraging targeted
                      alloy design, additive manufacturing of CuCrZr offers new
                      opportunities for optimizing the strength-to-conductivity
                      ratio in high-performance materials. Extensive
                      investigations were conducted to analyze the influence of
                      varying chromium concentrations (0 $wt.-\%$ to 2 $wt.-\%)$
                      on the property profile and solidification process of
                      CuCrZr. Temperature distribution calculations using a green
                      laser revealed high cooling rates of up to 5.5 x 106 °C/s,
                      which promote significant undercooling of up to 175 °C for
                      CuZr and 70 °C for CuCrZr, with curvature undercooling
                      being the dominant factor. These high cooling rates result
                      in the formation of a fine-grained microstructure
                      characterized by dislocation cells with diameters between
                      600 nm and 700 nm. After aging at 480 °C for two hours,
                      maximum strength was achieved. For CuCr2Zr, a strength of up
                      to 696 MPa and an electrical conductivity of 32.2 MS/m were
                      measured. Atom probe tomography revealed chromium
                      precipitates with an average radius of 5 nm.},
      cin          = {522110 / 520000},
      ddc          = {620},
      cid          = {$I:(DE-82)522110_20180901$ / $I:(DE-82)520000_20140620$},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2025-07248},
      url          = {https://publications.rwth-aachen.de/record/1017256},
}