Microstructural and mechanical characterization of self-passivating W-Eurofer joints processed by brazing technique

摘要

Self-passivating tungsten alloys have arisen as a potential candidate for the blanket first wall due to their high oxidation resistance and good thermal shock resistance. However, joining technologies have to provide a suitable process to conform the component. In this investigation, brazing technique was applied to join a self-passivating tungsten alloy to Eurofer using 50 mu m thick Cu interlayer. In addition, the use of post-brazing thermal treatment (PBTT) was also investigated to recover the as-received hardness of steel after the brazing cycle. The results showed the achievement of high brazeability joints in terms of metallic continuity and strength. With the PBTT the initial hardness of Eurofer was recovered but it gave rise to lower shear strength of the joint due to the softening of copper. The high strength and the fracture mechanism observed in some joints, propagating the fracture through the base material instead of the joint interfaces, showed the high adhesion properties achieved in both studied conditions.