Towards Radiation Tolerant Materials: Evaluation of Radiation Effects in interface-rich, nanostructured Cu-Fe-Ag

Michael Wurmshuber

Research output: ThesisMaster's Thesis

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Abstract

Newest developments in nuclear fission and fusion technology as well as planned long distance space missions demand novel materials to withstand harsh, irradiative environments. The main challenges for materials deployed in these applications are radiation-induced hardening and embrittlement as well as material swelling. The here underlying mechanisms are accommodation and clustering of lattice defects created by the incident radiation particles. Interfaces, such as free surface and phase boundaries, are known for trapping and annihilating defects and therefore preventing these radiation-induced defects from forming clusters. In this work, nanocomposites of different grain size out of Cu-Fe-Ag were fabricated using mechanical alloying via High Pressure Torsion. Additionally, a nanoporous material was produced using electrochemical dealloying. The impact of a proton- and a helium-ion irradiation treatment on the mechanical properties of the differently structured samples was investigated via nanoindentation. The influence of the helium-ion dose on the swelling behavior of the material was characterized using atomic force microscopy. The investigated interface-rich nanocomposites were proven to show tolerance against proton-irradiation damage. The bulk materials showed a slight decrease in hardness after irradiation, whereas the properties of the nanoporous material remain mostly unchanged. Extensive helium-ion implantation leads to bubble formation within the material and in further consequence to notable swelling and a foam-like behavior of mechanical properties. Depending on the helium dose and the interface-spacing in the material, different helium-bubble formation mechanisms were found to be dominant. The observed dose dependency of both, the swelling and the mechanical properties, for ultra-fine grained and nanocrystalline material can be explained by the bubble formation and -growth model proposed in this work.
Translated title of the contributionAuf dem Weg zu strahlungsbeständigen Materialien: Evaluierung von Strahlungseffekten in grenzflächenreichem, nanostrukturiertem Cu-Fe-Ag
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Kiener, Daniel, Supervisor (internal)
Award date23 Mar 2018
Publication statusPublished - 2018

Bibliographical note

embargoed until null

Keywords

  • nuclear materials
  • nanocomposites
  • radiation effects
  • HPT
  • mechanical alloying
  • electrochemical dealloying
  • UFG
  • nanocrystalline
  • nanoporous
  • proton irradiation
  • helium irradiation
  • nanoindentation
  • AFM

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