Microstructure and properties of Ti6Al4V/Cu dissimilar metals laser welded joints

Laser induced brazing reaction method was used to weld Ti6 Al4 V and Cu materials with Nb intermediate layer to solve the problem of Ti_xCu_ybrittle phase formed in Ti/Cu dissimilar metals welding which seriously reduced the mechanical properties of the joint. Laser beam was located at the Ti6 Al4 V/Nb interface,and heat input was controlled to make the Nb interlayer melt partially. The result showed that the fusion zone at the Ti/Nb interface is composed of（ Nb,Ti） solid solution. Relying on the unmelted Nb absorbing heat from the melting zone,Cu was melted to wet Nb,and a brazing joint layer composed of both Cu based and Nb based solid solution formed at the Nb/Cu interface. Thus,a hybid welding joint of two metallurgical welding zones was formed through one welding. Ti6 Al4 V and Nb were joined by fusion welding,while Nb and Cu were welded by brazing. The two metallurgical regions were separated by the unmelted Nb,which inhibited the formation of Ti_xCu_y brittle phase. The tensile strength of the joint was 225 MPa,and it showed a typical ductile fracture mode.