Understanding Interfacial Reactions in Ti-Ni Diffusion Couple

The diffusion phenomenon in the Ti-Ni binary system was investigated at a temperature of 1173 K. Microstructure and texture analysis revealed the formation of three stable intermetallic compounds, namely Ti₂Ni, TiNi, and TiNi₃, as well as two metastable intermetallic compounds, including Ti₃Ni₄ and Ti₂Ni₃, at the interfacial diffusion zone. The nucleation surface energy increase was analytically estimated, and marker experiments were conducted using thoria particles, both of which showed that Ti₂Ni was the first compound to form at the Ti-Ni diffusion interface. At a temperature of 1173 K, using the Wagner method, the integrated diffusion coefficients for the Ti₂Ni, TiNi, and TiNi₃ phases were calculated to be 3.53 × 10^-12, 18.1 × 10^-15, and 6.2 × 10^-15 m²/s, for, respectively.