Aufklärung der Verformungsvorgänge bei der Hochverformung

Translated title of the contribution: Examination of the Deformation Mechanisms of Severely Deformed Materials

Martin Hafok

Research output: ThesisDoctoral Thesis

Abstract

Face centred cubic polycrystalline and single crystalline metals were deformed by high pressure torsion (HPT) in order to study the evolution of microstructure and microtexture by scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD) measurements. The mechanical properties of the deformed materials were characterised by tensile tests and by measurement of the torque during severe plastic deformation. In addition, shear samples with special geometry were produced and deformed in in-situ measurements in order to reveal the deformation mechanism in the saturated structure size regime. The special design of the high pressure torsion device allows the production of a severely deformed microstructure at different rotational speed and at elevated temperatures. The microstructure is significantly influenced by the temperature and strain rate, but also the stacking fault energy or the chemical composition of an alloy contributes to the new formed microstructure. The influence of stacking fault energy and the contribution of lattice friction due to the alloy atoms of single phase brass alloys was investigated by SEM, transmission electron microscopy (TEM) and in mechanical tests. To separate both influences pure metals were deformed and their microstructures and flow stress curves were examined and compared with brass alloys to distinguish if the stacking fault energy or the lattice friction is dominating the evolution of the saturated microstructure.
Translated title of the contributionExamination of the Deformation Mechanisms of Severely Deformed Materials
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Clemens, Helmut, Assessor B (internal)
  • Pippan, Reinhard, Assessor A (internal)
Publication statusPublished - 2007

Bibliographical note

embargoed until null

Keywords

  • High Pressure Torsion
  • Single Crystal
  • Stacking Fault Energy
  • Hot Deformation
  • Shear Deformation

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