Vacuum brazing Ti₂AlNb / GH4169 alloy with (TiZrHf)₄₀(NiCu)₅₅Al₅ high-entropy amorphous filler metal

A high-entropy amorphous brazing filler metal (TiZrHf)₄₀(NiCu)₅₅Al₅ was designed for vacuum brazing of Ti₂AlNb alloy and GH4169 nickel-based superalloy. The effects of brazing parameters on the interfacial microstructure, mechanical properties and fracture behavior of Ti₂AlNb alloy/GH4169 nickel-based superalloy brazed joints were studied. The results showed that the brazed joints can be divided into Ti₂AlNb/ diffusion reaction zone (zone I)/brazing seam center zone (zone II)/diffusion reaction zone (zone III)/GH4169. The typical interface microstructure of brazed joints was Ti₂AlNb/B2 + Ti₂Ni(Al, Nb)/(Ti, Zr, Hf)(Ni, Cu)/(Ni, Cr, Fe, Ti)_ss + Cr-rich (Cr, Ni, Fe)_ss + Ni-rich (Cr, Ni, Fe)_ss/GH4169.With the increase of brazing temperature and brazing time, the shear strength of brazed joints increased first and then decreased. When the brazing temperature was 1020 ℃ and the brazing time was 15 min, the maximum shear strength of 237 MPa was obtained. The fracture analysis showed that the joint was mainly broken at zone of Ti₂Ni(Al, Nb) + (Ti, Zr, Hf) (Ni, Cu) + (Ni, Cr, Fe, Ti)_ss, and gradually expanded to the diffusion reaction zone. The fracture morphology showed typical cleavage fracture characteristics.