Fabrication of W/steel joint using hot isostatic pressing with Ti/Cu/Ti liquid forming interlayer

Diffusion boning is a preferred method to join tungsten and steel for the manufacturing of some components in the fusion technology. However, solid state diffusion bonding encounters many limitations in producing the W-steel modules because it is not tolerant of joints of variable width, and moreover, its reliability is highly sensitive to surface cleanliness and roughness. Therefore, the use of liquid phase forming interlayer is required to eliminate the need for high surface cleanliness and low surface roughness to ensure good contact and diffusion between the bonded surfaces, overcome the large differences in the physical properties of W and steel. In this work, an innovative method is applied for bonding W to steel using Ti/Cu/Ti eutectic forming interlayer. W-steel joint circular sleeve is prepared by a hot isostatic pressing diffusion bonding method at 1050 degrees C for 1 h under 100 MPa pressure. The microstructural examination and mechanical properties evaluation of the joints show that the bonding of W to steel is successful. Investigations of the bonded specimens show a hard reaction layer containing TiC at the interface between Cu and steel, which can weaken the bonding interface.