Transient liquid phase (TLP) bonding of TiAl using various insert foils

TiAl intermetallic alloys have been joined using the diffusion brazing technique with Ti insert foil metal combined with Cu, Ni or Fe foils. Defect-free joints can be fabricated successfully, no matter which kind of foil combination is used as insert metal. The interface structures of the joints were also investigated and results showed various interface structures in the joined zones. A mechanism for the development of the interface structure is proposed. It is suggested that the formation process of the liquid phase was responsible for the resulting interface structures. Post-bond heat treatment (PBHT) had no obvious effect on the interface structure of the joints because of the low diffusion coefficient of Cu, Ni and Fe in the parent material. Microhardness results showed a slight decrease in the joint area as a result of PBHT.