Low temperature and rapid diffusion bonding of Ni₃Al-based superalloy with Ni-based superalloy by spark plasma sintering

Conventional hot pressure diffusion bonding (HPDB) could result in undesired thermal and mechanical damages on base materials due to the high bonding temperature and long time. It has been a challenge to fabricate a reliable joint at a low bonding temperature and short time. In the present study, a spark plasma sintering (SPS) technique was used to resolve this challenge, and the microstructure and mechanical properties of the IC10/GH536 joints were systematically investigated. The results indicated that the pulsed current facilitated the micro-voids closure during the plasma activated diffusion bonding (PADB). At a relatively low temperature and short time (900 °C/30 min), a high joint shear strength of 541 MPa was obtained using the direct PADB, which was 4.74 times that of the direct HPDB joint. Increasing the bonding temperature to 1000 °C, a large number of M₂₃C₆ carbides formed at the grain boundaries and the bonding interface, which were the weak spots of the joint. In addition, by introducing a Ni foil to the PADB, the bonding temperature can be reduced to 800 °C and a joint shear strength of 424 MPa was obtained.