Stable bonding of W and ODS steel fabricated by TLP diffusion technology through inserting a novel composite interlayer Zr/Cu

Abstract Bonding of tungsten (W) with oxide dispersion strengthened (ODS) steel is an urgent challenge during the practical manufacturing process in many applications, including advanced nuclear reactor systems, military equipment, etc. To eliminate the generation of brittle intermetallic compounds Fe-W and relieve the residual thermal stresses, a novel composite interlayer Zr/Cu, for bonding W with ODS steel using the transient liquid phase (TLP) diffusion technology, was designed in this work. The bonding materials were prepared as a sandwiched structure of W/Zr-Cu/ODS steel in a vacuum diffusion bonding device. Interfacial structure and tensile strength of the bonded joints were investigated, and the processing parameters were optimized. After the bonding process, a reliable Cu/ODS steel interface could be built at all applied temperatures or holding times. Nevertheless, only as the bonding temperature was 1000 °C or even higher, the inserted Zr foil could be completely consumed and a stable W/Cu interface free from intermetallic compounds and micro-cracks was built. Additionally, the bonding ratio was gradually improved with increasing the bonding temperature or holding time. As a result, a high-strength W/Cu/ODS steel joint of ∼430.4 MPa could be fabricated at 1000 °C for a holding time of 60 min, and the bonding ratio was as high as 98 %, which provided a significant guide for the assembly of plasma facing components (PFCs).