High-strength vacuum diffusion bonding of Cu-plated, sandblasted W and CuCrZr alloy

W/CuCrZr alloy composite panels are promising plasma-facing components for use in future nuclear-fusion reactors. However, the intrinsic immiscibility of W and Cu makes joining them difficult. In this study, we developed a vacuum diffusion bonding method that involves sandblasting of the W substrate surface, Cu electroplating and annealing, and subsequent vacuum diffusion bonding to realize W/CuCrZr joints with high bond strength. The morphologies and structures of the W and W/CuCrZr joints were investigated by scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy. Sandblasting was found to induce the plastic deformation, roughening, and grain refinement of the W substrate surface. During Cu plating on the surface of the sandblasted W (and subsequent annealing), the Cu layer was embedded in micron-scale irregular pits on the sandblasted W surface, creating a tight bond. The shear bond strength (184 MPa) and bonding quality of a W/CuCrZr joint obtained with the sandblasting/Cu interlayer method was superior to those of a W/CuCrZr joint prepared by conventional vacuum diffusion bonding. The structural origins of this superior W/CuCrZr joint were related to a region of W and Cu interdiffusion with a thickness of approximately 30 nm. This improved vacuum diffusion bonding method for W and CuCrZr can facilitate the development of plasma-facing components for future nuclear-fusion devices. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

W/CuCrZr alloy composite panels are promising plasma-facing components for future nuclear-fusion reactors, and a vacuum diffusion bonding method involving sandblasting of the W substrate surface and Cu electroplating was developed to achieve high bond strength. The improved joint obtained with this method showed superior shear bond strength and bonding quality compared to conventional vacuum diffusion bonding methods.