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@PHDTHESIS{FernandezGutierrez:205833,
      author       = {Fernandez Gutierrez, Ricardo},
      title        = {{T}he {E}ffect of {S}olution {T}reatment on {C}ast
                      {A}l{C}u{M}n {A}lloys for {C}ylinder {H}ead {P}roduction},
      school       = {Vienna University of Technology},
      type         = {Dr.},
      address      = {Vienna},
      reportid     = {PUBDB-2015-00370},
      year         = {2014},
      note         = {blocked access to the doctoral thesis for the next three
                      years; Vienna University of Technology, Diss., 2014},
      abstract     = {New high temperature resistant materials are necessary to
                      increase the efficiency of combustion engines and thus
                      fulfil current environmental regulations. Al-Cu cast alloys
                      are potential candidates for cylinder head production. They
                      show higher tensile and low cycle fatigue strength than the
                      widespread Al-Si alloys, approaching even some grades of
                      ductile iron. However, they have been rarely used for serial
                      production owing to castability problems.In this work, the
                      evolution of the microstructure of the cast B206
                      (AlCu4.8Mn0.24Mg0.33), AlCu7 (AlCu6.5Mn0.4Zr0.22) and AF52
                      (AlCu4.7Mn0.4Ti0.17) alloys is investigated by two
                      dimensional (2D) and three dimensional (3D) methods as a
                      function of solution treatment (ST) time at 530 °C. Their
                      tensile, compressive and thermomechanical fatigue (TMF)
                      behaviour is correlated with the 3D microstructural changes
                      provoked by ST. Furthermore, the damage accumulation during
                      RT tensile tests is investigated three dimensionally by
                      means of synchrotron tomography.Part of the highly
                      interconnected aluminides segregated during casting
                      dissolves during the first 4 h of ST. The dissolution of Cu
                      into the -Al matrix provokes a strength increase in all
                      the alloys owing to precipitation hardening. The
                      strengthening of the alloys after ST is approximated as an
                      increase proportional to the capability of the -Al matrix
                      to dissolve Cu atoms. The B206 alloy shows the largest
                      strength and strengthening potential after ST. The volume
                      fraction (Vf) of aluminides remains constant for longer ST
                      times, as well as the strength of the alloys.All the alloys
                      experience an increase in ductility after the first 4 h of
                      ST. The AF52 alloy is in any ST condition the most ductile
                      alloy at RT and at 250 °C followed by B206 and AlCu7. This
                      is due to two different factors: i) the different kind of
                      aluminides present and ii) the effect of the solution
                      treatment. On one hand, needle / platelet-like Al7CuFe
                      (-Fe) aluminides are only present in B206 and AlCu7.
                      These aluminides are more detrimental in terms of ductility
                      than the pseudo-chinese script Al6(CuMnFe) (-Fe)
                      aluminides present in the AF52 alloy. Moreover aluminides in
                      the B206 and AlCu7 alloys present a larger fraction of
                      concave regions with small curvature radii than the AF52
                      alloy. These regions act as stress concentrators and lead to
                      a crack formation during tensile deformation. On the other
                      hand, the ST reduces the aluminides volume fraction and
                      partially dissolves the 3D aluminides network. Since cracks
                      tend to initiate and propagate through the aluminides
                      network, the ST provokes a reduction of crack nucleation
                      sites and propagation paths.Damage mainly occurs in the form
                      of cracks generated at large aluminides oriented
                      perpendicularly to the loading direction. These cracks
                      propagate through the aluminides network in alloys with
                      large aluminides Vf, which implies aluminides networks with
                      high interconnectiviy and connectedness. Shrinkage pores do
                      not play a significant role in the damage generation
                      process, particularly for the AlCu7 alloy. Porosity growth
                      with further crack propagation through the aluminides
                      network represents the other damage accumulation mechanism,
                      proper of alloys with lower aluminides Vf. This occurs
                      partially in the B206 alloy and particularly in the AF52
                      alloy. Void generation in the -Al matrix takes place only
                      at elevated temperature, i.e. 250 °C.Recommendations for
                      further alloy design are given based on the analysis of the
                      results obtained.},
      keywords     = {Dissertation (GND)},
      cin          = {FS-PE / DOOR},
      cid          = {I:(DE-H253)FS-PE-20120731 / I:(DE-H253)HAS-User-20120731},
      pnm          = {PETRA Beamline P05 (POF2-54G14) / FS-Proposal: I-20120707
                      EC (I-20120707-EC)},
      pid          = {G:(DE-H253)POF2-P05-20130405 / G:(DE-H253)I-20120707-EC},
      experiment   = {EXP:(DE-H253)P-P05-20150101},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://bib-pubdb1.desy.de/record/205833},
}