Microstructures of brazed and solid-state diffusion bonded joints of tungsten with oxide dispersion strengthened steel

The brazed and solid-state diffusion bonded (SSDB) joints of tungsten with oxide dispersion strengthened (ODS) steel were fabricated to use ODS steels as a structure component of first wall with tungsten as a plasma facing material in fusion blankets. Particular attention was paid to changes in the microstructure and chemical compositions in the bonding region. W was found to diffuse significantly into ODS steel, whereas there was only a limited diffusion of Fe and Cr from the ODS steel into W; these results are consistent with the diffusivity of each element. Interdiffusion multi-layer containing a layer with high concentration of B and of C was produced in the brazed joint and the SSDB joint, respectively.