Effect of welding temperature on microstructure and properties of titanium alloy diffusion welded joints

In order to solve problems of large brittleness,difficult processing and many defects of Ti-Zr-Ni-Cu intermediate layer,liquid phase diffusion welding technology of TC4 with Ni foil intermediate layer was studied. Welding temperature selection was based on Ni-Ti eutectic point and phase transition temperature of TC4 material. When welding temperature was below eutectic point 942 ℃,solid phase diffusion process occurred in the interface,there were larger pores in the joint,and Ni foil intermediate layer remained. When welding temperature was higher than eutectic point 942 ℃,solid-liquid diffusion process occurred in the interface. When welding temperature was 970 ℃,holding time was 120 min and welding pressure was 0. 1 MPa,the titanium alloys with Ni foil intermediate layer could achieve effective joining,the tensile strength of welded joints reached 946 MPa,which was close to the tensile strength of the base metal.