Investigation of tungsten/steel brazing using Ta and Cu interlayer

The brazing processes, using Ta and Cu interlayer respectively, were carried out to study the joining of W and steel with Ni-based amorphous foil filler. The W/Ta/steel and W/Cu/steel joints were conducted in vacuum at 1050 °C for 1 h. The interfacial microstructure and mechanical properties of joints were investigated by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and tensile strength measurement. The results show that a reliable bonding between W and steel could be obtained by using both Ta and Cu interlayer. The fracture sources of W/steel brazing joints were predominantly in the tungsten substrate near the brazing seam, which agrees reasonable well with the calculation result of finite element method (FEM). The average tensile strength of W/Ta/steel and W/Cu/steel joints were 257.8 MPa and 276.7 MPa respectively. Comparing with hard interlayer Ta, soft interlayer Cu could reduce residual tress in W substrate and improve the mechanical property more effectively.