Microstructure and Mechanical Properties of Diffusion Bonded Joint of TC4 Alloy Using Zr as Interlayer

Reliable diffusion bonding of TC4 alloy was achieved using Zr as interlayer. The interfacial microstructure was characterized by scanning electron microscopy (SEM), energy dispersive spectrum analysis (EDS) and X-ray diffraction (XRD). Effects of joining parameters on the microstructure and mechanical properties of the joints were investigated. The results indicate that (Ti,Zr) diffusion layer with uniform components transition forms at the interface of the joint, which consists of a large amount of lath-like a'-Ti (titanium martensite). With the increase of bonding temperature and holding time, the thickness of the diffusion layer increases, and the shear strength of the joint first increases and then decreases. The maximum shear strength is 190 MPa when the joint is bonded at 800 degrees C for 40 min under 5 MPa.