Transient thermal shock and helium ion irradiation damage behaviors of ODS-W/CuCrZr joints

The transient thermal shock and helium ion irradiation damage behaviors of oxide dispersion-strengthened tungsten (ODS-W)/CuCrZr alloy joints prepared by direct diffusion bonding and by improved diffusion bonding via surface nano-activation and Cu electroplating were studied. The surface morphologies and interface structures of the ODS-W/CuCrZr joints after thermal shock and He+ irradiation were investigated by atomic force microscopy, scanning electron microscopy, focused ion beam/scanning electron microscopy, and high-resolution transmission electron microscopy. The joint of ODS-W and CuCrZr prepared by the improved diffusion bonding method exhibited superior resistance to crack formation. No obvious plastic deformation was found on the ODS-W surfaces of the ODS-W/CuCrZr joints obtained by either bonding method after transient thermal shock (power density = 0.6 GW/m2). Interfacial debonding was observed to occur at the interface of W and Cu in the direct diffusion-bonded ODS-W/CuCrZr joint where Y2O3 particles exist, but did not occur in the joint prepared using the improved method. The nanostructures formed at the interface of the joint via the improved diffusion bonding method therefore elevated the radiation resistance of the joint. These results should be of relevance for the development of plasma-facing components in future nuclear fusion reactors.