Diffusion brazing of tungsten and steel using Ti-Ni liquid phase forming interlayer

A diffusion brazing process, for joining of tungsten (W) to steel using liquid phase forming interlayer, was developed for divertor application. Ti-Ni liquid forming interlayer was designed to overcome the large differences in physical properties between Wand steel, and to eliminate the need for a high bonding pressure to achieve intimate contact between the bonded surfaces. The diffusion brazing experiment was conducted at 1050 degrees C for 1 h under 0.2 MPa uniaxial pressure of contact. Metallographic analysis revealed that a good bonding was obtained at both the W/Ni and Ni/steel interfaces, and the reaction products were identified in the diffusion zone. A hard reaction layer containing TiC with a high hardness value of about 20.3 GPa was found at the Ni/steel interface. Joint tensile strength at different testing temperatures was evaluated and all the fracture occurred in the brittle carbide layer. (C) 2015 Elsevier B.V. All rights reserved.