Microstructures and mechanical properties of Ti3Al/Ni-based superalloy joints diffusion bonded with Ni and TiNiNb foils

• Published in: Welding in the world 2017-03, Vol.61 (2), p.375-381
• Main Authors: Ren, H. S., Wu, X., Chen, B., Xiong, H. P., Cheng, Y. Y.
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Diffusion welding; Materials Science; Metallic Materials; Research Paper; Shear strength; Solid Mechanics; Superalloys; Theoretical and Applied Mechanics
• ISSN: 0043-2288; 1878-6669
• DOI: 10.1007/s40194-016-0415-8

Dissimilar joining of Ti 3 Al-based alloy to Ni-based superalloy has been conducted with diffusion bonding method using Ni foil and TiNiNb alloy as interlayer. For the Ni foil, with the increase of bonding temperature, the joint strength increased firstly and then decreased. The joints bonded at 980 °C for 20 min with a pressure of 20 MPa presented the maximum shear strength of 207 MPa at room-temperature. During the bonding process, Ni foil reacted with Ti 3 Al-based alloy due to the strong affinity between elements Ti and Ni. The formation of Ni 2 Ti, AlNi 2 Ti, and Ni 3 Ti compounds at Ti 3 Al/Ni interface limited the mechanical properties of the joint. The use of the TiNiNb alloy decreased the formation tendency of brittle Ti-Ni phases to some extent and only little Ti 2 Ni phase was visible in the joint. The shear strength of 209 MPa was obtained under the condition of 980 °C/10 min/20 MPa, close to that obtained through Ni foil. The (Ni,Ti,Nb,Fe,Cr) multi-component phase formed at TiNiNb/GH536 interface became the new weak link of the joint.