TY - THES

T1 - Towards Radiation Tolerant Materials: Evaluation of Radiation Effects in interface-rich, nanostructured Cu-Fe-Ag

AU - Wurmshuber, Michael

N1 - no embargo

PY - 2018

Y1 - 2018

N2 - 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.

AB - 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.

KW - Werkstoffe in Kernenergie

KW - Nanokomposite

KW - Strahlungseffekte

KW - HPT

KW - mechanisches Legieren

KW - elektrochemisches Ätzen

KW - UFG

KW - nanokristallin

KW - nanoporös

KW - Protonenbestrahlung

KW - Heliumbestrahlung

KW - Nanoindentation

KW - AFM

KW - nuclear materials

KW - nanocomposites

KW - radiation effects

KW - HPT

KW - mechanical alloying

KW - electrochemical dealloying

KW - UFG

KW - nanocrystalline

KW - nanoporous

KW - proton irradiation

KW - helium irradiation

KW - nanoindentation

KW - AFM

M3 - Master's Thesis

ER -