Investigation of tungsten/steel diffusion bonding with Ni-Fe cladding on tungsten substrate

In this work, a diffusion bonding approach, for the joining of W and steel using the Ni-Fe cladding layer, was developed for nuclear component application. First, a 10 mu m thick Ni-Fe alloy cladding layer was deposited on the pure W substrate through high temperature cladding technology. Then the diffusion bonding was carried out in vacuum at 1050 degrees C for 1 h with 10 MPa to join the cladded W and steel. The bonded specimens were characterized a typical W-Ni-Fe alloy with continuous element distribution at the joining interface, which strengthens the bonding interface. Joint tensile strength at different testing temperatures was investigated and results showed the fracture all occur in tungsten side near the joining interface due to residual stresses concentration. The hardness distribution across the joining interface was also determined.