The design of a new Ti-Zr-Cu-Ni-Ag brazing filler metal for brazing of titanium alloys

Titanium alloys with light weight and high strength at 300–400 °C have been widely used in aerospace industry. Vacuum brazing technique with the advantage of low stress and high efficiency for Ti-based alloy has been developed for manufacturing the components in complicated structure such as heat exchanger. The newly designed filler material as Ti-12.5Zr-13.7Cu-11.6Ni-2.2Ag wt% was used for brazing the dissimilar joint of CP-Ti (as TA2) and Ti6Al4V. A sound joint with strength as 469 MPa and impact toughness as 4.5 ~ 5.0 J/cm 2 were achieved by brazing process as 875 °C/10 min. A few amounts of intermetallics as TiNi 3 and Ti 2 Cu phases with the fraction as 7.82 vol.% and 0.0126 vol.%, respectively, was examined in the joint, which were thought to balance the strength and the ductility of it. The fine distributed phase of TiNi3 with soft orientation as {0001}[11–20] was benefit for the ductility of the TA2-Ti6Al4V joints.