Phase transition induced low temperature diffusion bonding of Zr-4 alloy using a pure Ti interlayer

In this paper, a low-temperature sealing of Zr-4 alloy induced by α→β phase transitions by using a pure Ti interlayer was reported. Both Ti and Zr compositions show smooth transition at the Ti/Zr interface when no phase transition happened. While a Ti, Zr elemental distribution plateau, corresponding to a light gray diffusion zone, was found at the Ti/Zr interface after a β-(Ti, Zr) phase transition happened. Results show that, to achieve the same shear strength of 294 MPa, the bonding temperature was reduced by 100 ℃ after using the pure Ti foil interlayer. Molecular dynamics (MD) simulation data show that the diffusion coefficients of Zr in β-(Ti, Zr) and α-(Ti, Zr) are 0.194 × 10⁻¹¹ m²/s and 0.015 × 10⁻¹¹ m²/s respectively, which further proves the β-(Ti, Zr) phase transition zone can indeed facilitate the diffusion of Zr-4/Zr-4 couples and lower the diffusion bonding temperature.