Microstructure and mechanical properties of laser welding of Ti6Al4V to Inconel 718 using Nb/Cu interlayer

To improve the quality of the joints between Ti6Al4V and Inconel 718, fiber laser welding with Nb/Cu multiinterlayer was attempted by laser welding induced brazing-welding method. The hybrid joint comprising different metallurgical areas was created based on fusion welding and brazing welding mechanisms through one welding. Ti6Al4V and Nb well bonded by the fusion welding, and the fusion zone was characterized by the formation of (alpha + beta Ti, Nb) solid solutions. Nb and Inconel 718 were joined by brazing because of the melting of Cu foil, and the Nb/Cu/Inconel 718 interface mainly consisted of the Nb-based, Cu-based, and Ni-based solid solutions. The joint failed in the Nb/Cu/Inconel 718 interface with the maximum strength of 260 MPa, exhibiting brittle-like failure behavior due to the formation of voids and microcracks at the Nb/Cu/Inconel 718 interface. The addition of Nb/Cu multi-interlayer can help prevent the formation of IMCs and improves the mechanical properties of the joint.