Brazing ZrO2 ceramic to Ti–6Al–4V alloy using NiCrSiB amorphous filler foil: Interfacial microstructure and joint properties

Reliable brazing of ZrO2 ceramic and Ti–6Al–4V alloy was achieved using NiCrSiB amorphous filler foil. The interfacial microstructure of ZrO2/Ti–6Al–4V joints was characterized by scanning electron microscope, energy dispersive spectrometer and micro-focused X-ray diffractometer. The effects of brazing temperature on the interfacial microstructure and joining properties of brazed joints were investigated in detail. Active Ti of Ti–6Al–4V alloy dissolved into molten filler metal and reacted with ZrO2 ceramic to form a continuous TiO reaction layer, which played an important role in brazing. Various reaction phases including Ti2Ni, Ti5Si3 and β-Ti were formed in brazed joints. With an increasing of brazing temperature, the TiO layer thickened gradually while the Ti2Ni amount reduced. Shear test indicated that brazed joints tend to fracture at the interface between ZrO2 ceramic and brazing seam or Ti2Ni intermetallic layer. The maximum average shear strength reached 284.6 MPa when brazed at 1025 °C for 10 min. - Graphical Abstract: Interfacial microstructure of ZrO2/TC4 joint brazed using NiCrSiB amorphous filler foil was: ZrO2/TiO/Ti2Ni + β-Ti + Ti5Si3/β-Ti/Widmanstätten structure/TC4. - Highlights: • Brazing of ZrO2 ceramic and Ti-6Al-4V alloy was achieved. • Interfacial microstructure was TiO/Ti2Ni + β + Ti5Si3/β/Widmanstätten structure. • The formation of TiO produced the darkening effect of ZrO2 ceramic. • The highest joining strength of 284.6MPa was obtained