Microstructure and properties of hot isostatic pressing diffusion bonding steel/tungsten joint with V/Nb composite interlayer

In this paper, steel and tungsten were successfully bonded using hot isostatic pressing diffusion bonding with V/Nb composite interlayer. The interface structure and shear strength of the joints under high temperature-low pressure process (1 050 ℃, 20 MPa) and low temperature-high pressure process (950 ℃, 100 MPa) were investigated separately. The results show that the joints under high temperature-low pressure process and low temperature-high pressure process both have a W/Nb/V/steel four-layer structure and the shear strengths of the joints are 96.9 MPa and 104.2 MPa respectively. The fracture of the joints all appears at the Nb/V interfaces with no obvious chemical reaction. Compared with the joint under high temperature-low pressure process, reducing the bonding temperature and increasing the bonding pressure will benefit to form a dense joint, but will not promote the diffusion of elements at the weak interface (Nb/V) and significantly increase the shear strength of the joint.