Fig. 1 a Microstructure and b XRD patterns of TC4 alloy, and c DSC curves of Ti-37.5Zr-15Cu-10Ni filler metal

Fig. 2 Schematic diagrams of a brazing assembly, b shear test experiment and c bonding cycle curve

Fig. 3 Typical microstructure of the joint brazed at 925 °C for 10 min: a, b microstructure of brazed joints, c elemental distribution across the joint, d-f different magnification of brazed joints and b1-b8 the corresponding elemental distribution of Ti, Al, V, O, Mg, Ni, Cu and Nb

Fig. 4 Crystal structure and composition of phases at bonding interface: a HAADF pattern of bonding interface, a1-a8 the corresponding elements mapping of Ti, Zr, Cu, Ni, V, Mg, Al, and O, respectively, b, c crystal structure of phase A and B deduced by a SAED patterns, d HRTEM image of the phase interface

Fig. 5 Crystal structure and composition of phases at bonding interface: a, d HAADF pattern of bonding interface, a1-a8, d1-d8 the corresponding elements mapping of Ti, Zr, Cu, Ni, V, Mg, Al, and O, respectively, b, c and f crystal structure of phase deduced by a SAED patterns, e HRTEM image of the phase C

Fig. 6 Microstructures and interfaces of joints brazed at a 875 °C, b 900 °C, c 925 °C, d 950 °C, e 975 °C and f 1000 °C for 10 min, respectively

Fig. 7 Schematic diagram of brazing interface formation: a melting of filler metals, b isothermal solidification process, c, d cooling from different temperature, and e schematic phase diagram of Ti (Zr)-Cu (Ni)

Fig. 8 Microhardness and modulus of joints with different brazing temperature: a microhardness distribution and b modulus of the joints brazed at 900 and 975 °C

Fig. 9 Shear strength mechanical property of joints at room temperature

Fig. 10 a Atomic size difference of the elements with respect to Cu atom (smallest in size) [36] and b ΔHmix (kJ/mol) between Ti-Zr-Cu-Ni and Al [37]