Diffusion bonding of Ti/Ni under the influence of an electric current: mechanism and bond structure

The diffusion bonding between Ti and Ni was investigated in the presence and absence of an imposed electric current. Bonding was carried out over the temperature range of 873–1123 K and the current density range of 255–350 A/cm 2 . The formation and sequence of evolution of the three intermetallic phases, TiNi 3 , TiNi, and Ti 2 Ni, were investigated and discussed in light of calculations of Gibbs free energies of formation and interfacial energies associated with their nucleation. Within the experimental times and in the presence of a current, the growth of the three phases was parabolic. The evolution of the TiNi phase required an incubation period, while the relatively high growth rate of TiNi 3 suggests the possibility of another mechanism. The growth of all phases was enhanced by the application of a direct current, with no apparent dependence on its direction.