Study on the microstructure and mechanical properties of Ti-Zr-Cu-Ni amorphous filler brazed Inconel 718 and 3D printed TC4 alloy

In this study, the Ti-Zr-Cu-Ni amorphous brazing filler was used to achieve vacuum brazing between TC4 titanium alloy manufactured by selective laser melting (SLM) and Inconel 718 superalloy. The microstructure of the brazed joint was mainly TC4 base metal/Widmanstätten structure/β-Ti + Ti2Cu/(Ti, Zr)2(Cu, Ni)/(Ti, Zr)2(Cu, Ni) + α-Ti/Fe2Ti + Cr7Ni3 + TiNi3 + Ni(Fe, Cr) solid solution/Inconel 718 base material. The influence of different brazing temperatures and brazing times on the microstructure and mechanical properties of the joint was studied. The distribution of residual stresses in the joints was analyzed by nanoindentation and EBSD. The mechanical properties of the intermetallic compounds in the joints and their effects on the mechanical properties of the joints were also investigated. When the brazing temperature was 930 °C and the brazing time was 20 min, the brazed joints with optimal mechanical properties were obtained, and the average shear strength of the joints reached 111.2 MPa. Fracture analysis showed that the cracks sprouted in the (Ti, Zr)2(Cu, Ni) and (Ti, Zr)2(Cu, Ni) + α-Ti two-phase zone and extended in this region. The fractured form was a brittle fracture, and the mechanical properties of the joint were dominated by Ti-based intermetallic compounds.