Microstructure and mechanical properties of diffusion bonded joints between tungsten and F82H steel using a titanium interlayer

Diffusion bonding between W and ferritic/martensitic steel F82H using a Ti interlayer was carried out in vacuum at temperature range of 850–950 °C for 1 h with 10 MPa. Metallographic analysis with field-emission scanning electron microscopy revealed excellent bonding at both W/Ti and Ti/F82H interfaces. The chemical compositions of the reaction products were analyzed by energy dispersive spectroscopy and their existence were confirmed by X-ray diffraction technique. α–β Ti solid solution was detected at W/Ti interface, while the reaction phases at Ti/F82H interface are dependent on the joining temperature. Joint strength was evaluated and the variations in strength of the joints were significantly related to the microstructural evolution of the diffusion zone. All the joints fractured at Ti/F82H interface during shear testing. The hardness distribution across the joining interfaces was also determined.