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@PHDTHESIS{Delis:984074,
      author       = {Delis, Wassilios Johannes},
      othercontributors = {Korte-Kerzel, Sandra and Springer, Hauke Joachim},
      title        = {{I}nvestigation of solid solution effects on texture and
                      dislocation activity in wrought lean-alloyed ternary
                      {M}g-{A}l-{C}a alloys},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2024-03843},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2024},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, Rheinisch-Westfälische Technische
                      Hochschule Aachen, 2024, Kumulative Dissertation},
      abstract     = {The development of high strength and ductile Mg alloys is a
                      major focus due to Mg’s lightweight properties, which make
                      it valuable in industries such as automotive and aerospace,
                      as well as ist potential to reduce greenhouse gas emissions.
                      However, Mg alloys face challenges in terms of room
                      temperature formability. Research has explored various
                      parameters, including texture modification and alloying with
                      elements like Y and rare-earth elements to improve
                      ductility. Recent studies suggest that the addition of Y and
                      rare-earth elements activates non-basal slip systems,
                      thereby improving formability. A joint computational and
                      experimental study found the Mg-Al-Ca systemto be promising,
                      offering similar properties with low cost elements.This work
                      aims at a deeper understanding of the Mg-Al-Ca system by
                      investigating the elemental effects on mechanical
                      properties, texture and slip system activity. Different
                      alloying compositions were synthesised and analysed while
                      maintaining the same processing parameters. It was shownthat
                      the addition of Al and Ca significantly increases the
                      strength and ductility of Mg, but onlythe combination of
                      both Al and Ca gives to the highest values of both. Ca has
                      an intrinsic grainrefinement effect on the alloy, pinning
                      the grain boundaries and therefore leading to weaker
                      basaltextures. Also, the amount of Ca is important as Al
                      reduces the solubility of Ca in Mg. Adjustingthe alloying
                      contents of Ca and Al not only allows weak as-recrystallised
                      textures but also allowsweak textures to be maintained
                      during further cold rolling. In general, the effect of Ca on
                      bothgrain refinement and texture can be seen at very low Ca
                      additions (0.005 $wt.-\%).$ However, theco-dependence of Al
                      and Ca significantly increases the complexity of the alloy
                      system. Al shows notonly an effect on solid solution
                      strengthening, but also increases the presence of 〈c +
                      a〉 dislocations. APT at a 2nd order pyramidal slip line
                      also shows Al segregation at the dislocation. Access to the
                      CRSSs of non-basal slip systems with MP compression was not
                      successful, because basal slip was ubiquitous even at very
                      low Schmid factors. Consecutive TEM shows that non-basal
                      slip was active but mainly stored in the matrix. It was also
                      found, that 〈c + a〉 dislocations were more abundant near
                      boundaries such as grain or twin boundaries, suggesting that
                      these defects have favourable strain fields allowing easier
                      activation of 〈c + a〉 slip there than in the matrix.
                      Further investigations using HR-STEM are underway to
                      investigate the effect of Al on the activation ofthe slip
                      system. In summary, this work provides a fundamental
                      understanding of the Mg-Al-Ca alloy system, butits practical
                      application depends on optimising the alloy content and
                      further research to improve ductility. This includes, in
                      particular, exploring the effect of the Al:Ca ratio in order
                      to maximisethe beneficial Ca effect while maintaining the Al
                      effect, and also to gain a better understanding of the
                      mechanisms behind the activation of 〈c + a〉
                      dislocations.},
      cin          = {523110 / 520000},
      ddc          = {620},
      cid          = {$I:(DE-82)523110_20140620$ / $I:(DE-82)520000_20140620$},
      pnm          = {SFB 1394 A01 - Mischkristalleffekte auf die Bildung von
                      Defektphasen in Ni-X Mischkristallen (A01) (437400724) / SFB
                      1394: Strukturelle und chemische atomare Komplexität –
                      Von Defekt-Phasendiagrammen zu Materialeigenschaften},
      pid          = {G:(GEPRIS)437400724 / G:(GEPRIS)409476157},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2024-03843},
      url          = {https://publications.rwth-aachen.de/record/984074},
}