Vacuum brazing of Ti3Al-based alloy to TiAl using TiZrCuNi(Co) fillers

Abstract A traditional Ti 13Zr 21Cu 9Ni (wt.%) filler metal was used to join Ti 3 Al-based alloy and TiAl intermetallics, and the joints brazed at 1213–1233 K for 600 s presented a shear strength of 113–149 MPa at room temperature. For the improvement of the joint strength a Ti Zr Cu Ni Co filler metal was designed. The shear strength of the joints brazed with the Ti Zr Cu Ni Co filler at 1283 K for 300 s reached 278 MPa, increased about 86.6% compared with the Ti Zr Cu Ni system filler. The overall hardness in the joint brazed with the Ti Zr Cu Ni Co filler was uniformly lower than the joint brazed with Ti Zr Cu Ni filler. The Ti 3 Al/TiAl joint brazed with Ti–Zr Cu Ni mainly consisted of Ti 2 Al, α 2 -Ti 3 Al and the residual filler metal of Ti(Cu, Al) 2  + CuZr. The phase sequence within the Ti 3 Al/TiAl joint brazed with Ti Zr Cu Ni Co filler from TiAl side to Ti 3 Al side can be described as the follows: TiAl substrate/Ti 2 Al +α 2 -Ti 3 Al/α 2 -Ti 3 Al + Ti-rich phase/residual filler metal/Ti-rich phase/Ti-rich phase + O-Ti 2 AlNb/Ti 3 Al substrate, and the fracture surface of the corresponding joint was characterized by Ti-rich phase, indicating that compared with the traditional Ti Zr Cu Ni filler the joint ductility was increased to a great extent.