Transient liquid phase diffusion bonding of Ti-24Al-15Nb-1Mo alloy to TiAl intermetallics

Transient liquid phase (TLP) diffusion bonding of a Ti3Al-based alloy and TiAl intermetallics was firstly conducted with Ti-15Cu-15Ni (wt%) interlayer. Ti2Al layer, α2-Ti3Al band, Ti-rich phase, Ti2Ni and Ti2Cu compounds were formed within the joint and the joint showed a low shear strength of 74-79 MPa. For the newly designed Ti-Zr-Cu-Ni-Co system filler alloy, the bonded joint mainly consisted of Ti-rich phase, Ti2Al layer, (Ti, Zr)2Al phase and (Ti, Zr)3Al dissolved with Cu, Ni and Co. The joints bonded at 1253 K for 600 s with a pressure of 2 MPa presented the maximum shear strength of 435 MPa at room temperature, and the strength of 234 MPa was maintained at 873 K. CuZr and Zr2Ni phases rather than Ti2Ni and Ti2Cu compounds were formed within the latter joint. The formation of the CuZr and Zr2Ni phases as well as the plastic α-Ti phase increased the joint ductility to a great extent.