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@PHDTHESIS{Bitzer:151907,
      author       = {Bitzer, Martin},
      title        = {{P}ulvermetallurgische {F}unktionsbauteile aus {N}i{T}i-
                      und {N}i{T}i-{X} {L}egierungspulvern},
      volume       = {206},
      school       = {Universität Bochum},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2014-01754},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {140 S.},
      year         = {2014},
      note         = {Universität Bochum, Diss., 2013},
      abstract     = {Powder metallurgy is an attractive option for manufacturing
                      of NiTi parts considering its limited machinability due to
                      the shape memory effect. Nevertheless, the industrial
                      implementation of this process for NiTi-alloys is not
                      trivial due to need of demonstrating reproducible shape
                      memory behaviour which is strongly influenced by the high
                      affinity for oxygen and carbon. O- and C-rich phases as well
                      as the precipitation of Ni-rich Ni$_{4}$Ti$_{3}$ occuring by
                      the cooling process from process temperature influence the
                      transformation behaviour. In the present work, each step of
                      the powder metallurgical production-chain is discussed,
                      starting from prealloyed NiTi-powder and ending with
                      functional components. Three innovative applications with
                      high industrial relevance were used for demonstrating the
                      high potential of P/Mtechnologies: Orthodontic NiTi-brackets
                      with pseudoelastic properties at body temperature were
                      manufactured by Metal-Injection-Moulding (MIM). Required
                      phase transformation temperatures were adjusted by heat
                      treatment. Fully pronounced shape memory effect was
                      demonstrated using the one way effect. Futhermore it was
                      shown, that blending prealloyed NiTi-powder with elemental
                      Ni or Ti is a promising approach for shifting transformation
                      temperatures as well as reducing the residual porosity after
                      sintering by the formation of an eutectic melt. NiTi is an
                      attractive material for cavitation resistant coatings
                      considering its clearly pronounced damping behaviour based
                      on its pseudoelastic properties. Cavitation might cause
                      significant wear in technical applications like turbine
                      blades in hydropower plants or pump components. Coating of
                      exposed surfaces by wear resistant materials would be highly
                      attractive for extending lifetime of related systems. A
                      promising powder metallurgical processing route for
                      manufacturing such coatings is Low Pressure Plasma Spraying
                      (LPPS). In the present work, NiTi-layers were produced by
                      LPPS, starting from prealloyed NiTi-powder. Cavitation
                      resistance depending on LPPS parameters, surface treatment
                      and layer thickness was investigated. The study is
                      accompanied by characterization of microstructure and phase
                      transformation behaviour. Compared to binary NiTi, ternary
                      NiTi-X-alloys differ in phase transformation behavior and
                      can thereby enlarge the application field of
                      shape-memory-alloys. In the case of addition of elemental
                      Nb, broadening of hysteresis between austenitic and
                      martensitic phase transformation temperatures after plastic
                      deformation of the Nb-phase is a well-known effect, which is
                      the key of function of coupling elements already established
                      on the market. In the present study, Nb, W and Ag were
                      blended with prealloyed NiTi-powder and hot isostatic
                      pressing was used for manufacturing NiTi-Nb, NiTi-Ag and
                      NiTi-W-alloys for the production of couplings.
                      Microstructures, interdiffusion phenomena, phase
                      transformation behavior, and impurity contents were
                      investigated aiming on better understanding of the influence
                      of insoluble phases on bulk properties of NiTi-SMAs. Due to
                      its antibacterial properties, NiTi-Ag is furthermore a
                      promising alloy for medical implants. Biocompatibility and
                      toxicity with respect to bacteria were investigated for
                      evaluating the potential of the material for this
                      application.},
      keywords     = {Dissertation (GND)},
      cin          = {IEK-1},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {123 - Fuel Cells (POF2-123)},
      pid          = {G:(DE-HGF)POF2-123},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/151907},
}