Development of W-composites/EUROFER brazed joints for the first wall component of future fusion reactors

The present work describes a joining procedure between two different tungsten composite materials (W–2Y₂O₃ and W–1TiC) with reduced activation ferritic–martensitic steel (Eurofer). The results indicated the achievement, in both cases, of high quality W-composites/Eurofer joints using 80Cu–20Ti as filler material. The braze is constituted by several ternary Cu–Ti–Fe phases distributed along a Cu-matrix, which acts as ductile phase capable of relieving the residual stresses, which could be produced during the service life of the component. Some cracks growing from W–braze interface into the base material have been detected. They are originated by the stresses produced during the cooling stage of the brazing cycle. Regarding the strength of the joints, similar shear strengths of both joints were obtained (∼105 MPa). These values were slightly lower than the ones obtained when pure tungsten was used as the base metal. (paper)