Simultaneously increasing strength and ductility of nano-crystalline Cu-Zn-alloys made from powderous raw materials

Research output: ThesisMaster's Thesis

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Abstract

Nano-crystalline materials produced by severe plastic deformation tend to exhibit superior strength compared to their coarse-grained counterparts. Their ductility, however, stays disappointingly low. Studies have shown that alloying can reduce the stacking fault energy, thus enable additional deformation mechanisms, such as mechanical twinning. Building on former investigations of Zhao et al., this work shows the utilization of this principle for samples produced by ball milling and high-pressure torsion. Powders in compositions of pure Cu, and Cu with 10, 20, and 30 wt.% Zn were used as raw materials. Saturation of the microstructure was determined by Vickers hardness measurements and by scanning electron microscope imaging, while the grain size was analyzed by transmission electron microscopy investigations. Further, tensile tests were performed to measure the mechanical properties. Despite the same compositions and therefore the same stacking fault energies as in the references, the fabricated samples showed smaller mean grain sizes and an increased tendency for twinning. Thus, improved values for yield-strength and ultimate strength for compositions up to 20 wt.% Zn, as well as significantly higher total elongations for compositions up to 10 wt.% Zn could be achieved.
Translated title of the contributionGleichzeitiges Erhöhen von Festigkeit und Duktilität von aus pulverförmigen Ausgangsmaterialien hergestellten, nanokristallinen Cu-Zn-Legierungen
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Kiener, Daniel, Co-Supervisor (internal)
Award date31 Mar 2023
DOIs
Publication statusPublished - 2023

Bibliographical note

no embargo

Keywords

  • copper alloys
  • stacking fault energy
  • mechanical twinning
  • strength
  • ductility
  • high-pressure torsion
  • ball milling

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