Speaker
Description
A significant challenge on the path to magnetic confinement fusion power plants is the robust exhaust of power and particles. In particular, plasma‑facing components (PFCs) in the divertor region must endure challenging particle and heat fluxes while simultaneously sustaining damage from fusion‑neutron irradiation. This leads to a progressive degradation of key material properties such as strength, toughness and thermal conductivity. For next‑step devices — including ITER and DEMO‑class reactors — divertor target concepts have therefore been developed that, in essence, join a monolithic tungsten (W) armor to a high‑conductivity copper (Cu) alloy heat sink. This architecture is intended to combine the plasma‑compatibility of W with efficient heat removal capability by a Cu‑based structure. In such a design, the mechanical stability of Cu‑based alloys is essential and must be ensured throughout the PFC's operational lifetime. However, the degradation of mechanical properties of Cu-alloys due to high-temperature operation and neutron irradiation remains a substantial challenge for divertor PFC design. One promising route to maintain the mechanical properties at elevated temperatures and even under neutron irradiation is the use of high-strength drawn W fibers in a Cu alloy matrix. The contribution will present work regarding the characterization of such advanced composite materials. In this context, material specimens based on W fiber weaves with two different fiber volume fractions have been infiltrated with oxygen-free Cu, Cu-Chromium and Cu-Chromium-Zirconium alloy, in order to study the influence of the different preforms and matrix materials on the composites properties. The specimens were analyzed by means of scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) to reveal their microstructures after infiltration. In terms of mechanical property characterization, tensile tests at room temperature and above have been carried out while the specimens showed an increased strength compared to the monolithic Cu-based alloy matrices. Additionally, fractography was carried out to understand the failure mechanism. The results of this study led to the fabrication of tensile specimens for a neutron irradiation campaign in the BR2 reactor (Mol, Belgium) which will be conducted in the near future.