Microstructure and tensile properties of nickel-based superalloy K417G bonded using transient liquid-phase infiltration

• Ni-based superalloy K417G is bonded using transient liquid-phase infiltration.
• The locally isothermal solidification leads to the formation of voids.
• The formation of voids and Cr5B3 borides lead to reduction of tensile properties.

Nickel-based superalloy K417G samples with 2.2 mm gap are bonded by transient liquid-phase infiltration (TLI). The microstructure and tensile properties of TLI joint have been investigated. The results show that the nonuniform microstructure is obtained in the TLI joints. The voids, Cr5B3 borides and (Cr, W)B borides are presented in the TLI region. The no isothermal solidification of the transient TLI joint leads to the formation of Cr5B3 borides. The tensile properties of TLI joint samples are lower than that of base sample, especially the ductility. The observation of fracture surfaces show that the Cr5B3 borides are the main cause, which leads to the decrease of ductility. The Cr5B3 borides can act as the crack initiation and also accelerate the propagation of cracks during the deformation.