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

Abstract

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.

Keywords

• W
• CuCrZr
• Vacuum diffusion bonding
• Sandblasting
• Cu plating
• Plasma-facing components