Diffusion Bonding of Ti-6Al-4V Alloy and AZ31B Using Copper Interlayer
The experimental investigation of diffusion bonding of titanium alloy(Ti-6Al-4V) to magnesium alloy(AZ31B) in vacuum was carried out by using pure copper as transition metal. The microstructure of the welded joints was studied by SEM, EDS, etc and the mechanical properties of the samples were tested by tensile experiments. The results show that: under the condition of 530℃ in holding time for 45 min and pressure 2.5MPa, the microstructure at interface zone of diffusion brazing joint includes γ-Cu solid solution, Cu3 Ti, Cu2 Al, Mg-Cu-Al ternary intermetallic compounds, Mg17(Cu,Al)12and(α-Mg+Mg2Cu) eutectic structure. When the welding temperature is 520℃, there is no liquid in AZ31B/Cu interface zone,and it is unable to realize the connection of AZ31 B and Ti-6Al-4V. At welding temperature of 530℃, the eutectic structure and intermetallic compounds are simultaneously distributed in the interface zone to form a metallurgical bond. As the welding temperature is 550℃, the eutectic structure disappears and the Mg-Cu-Al ternary intermetallic compounds show a continuous network distribution. As the holding time increasing, the shear strength shows an increasing trend at first and then decreasing.When the welding process is 530℃ keeping for 30 min, the welding pressure is 2.5 MPa, the highest shearing strength of the welded joint can reach 61 MPa.