Microstructural evolution and mechanical properties of AlCoCrFeNi high-entropy alloy joints brazed using a novel Ni-based filler

Highlights: • A high-quality AlCoCrFeNi high-entropy alloy brazed joint with the fusion zone similar to the base metal was achieved. • The brazed joint exhibited a desirable high-temperature stability with minor degradation of joint strength after high-temperature annealing. • The mechanisms of interfacial phase evolution and joint strengthening were discussed. -- Abstract: This paper reported a route to fabricate a high-performance high-entropy alloy (HEA) brazed joint with the fusion zone similar to the base metal, in which the brazing of a Ni-containing AlCoCrFeNi HEA using a novel Ni-based filler was investigated at 1150–1350 °C for 0–45 min. A microstructure similar to the base metal was received in the fusion zone through proper interface control, thus the joint shear strength obtained was approximately three times (687.2 ± 23.2 MPa) in contrast to that of the joint with the heterogenous interface (199.4 ± 2.8 MPa). The strengthening mechanism was attributed to the high-entropy solid solution, precipitation strengthening and grain refinement occurring in the joint. The highest joint strength of 687.2 ± 23.2 MPa was received at 1300 °C for 15 min with the fracture mainly happening in the base metal. The brazed joint exhibited desirable high-temperature stability with minor degradation of joint strength (∼3%) after annealing of 800 °C for 240 h. The excellent joint performances are potential for high temperature applications.