A novel sandwich-structured interlayer enabled high-performance GH4169D TLP bonded joint

Herein, a novel sandwich-structured interlayer (Ag30Cu37Zn32Sn/Cu 51.25 Zn 26.25 Ni 9 /Ag30Cu37Zn32Sn) was designed to transient liquid phase (TLP) bonding GH4169D superalloys. The interfacial microstructure, mechanical properties and fracture behaviour of GH4169D joints were investigated. The bonded interface was composed of (Ag, Cu, Zn) ss and (Cu, Zn, Ni) ss . A wider diffusion-affected zone including (Cu, Zn, Ni) ss and Cr-rich (Cr, Fe, Co) ss was formed at the interface with Ni 9 interlayer. A shear strength of 598 MPa was obtained at 890 °C for 80 min. (Ag, Cu, Zn) ss possessed low interface stiffness due to its small Young's modulus and Poisson's ratio. During the shear process, the soft-hard interface between (Ag, Cu, Zn) ss and (Cu, Zn, Ni) ss was prone to stress concentration, which induced initial crack initiation.