Diffusion bonding of AlCoCrFeNi2.1 eutectic high entropy alloy to GH4169 superalloy

Eutectic high entropy alloys possess both excellent plasticity and high strength. To explore their potential engineering applications, the diffusion behavior of elements, the interfacial microstructure and shear strength of the diffusion bonded joint between AlCoCrFeNi2.1 eutectic high entropy alloy and GH4169 superalloy were studied. The width of diffusion zone increased with bonding temperature increasing and the voids gradually disappeared due to the increased diffusion rate of the elements and the high-temperature creep. A new layer of face-center-cubic (FCC') phase, which was caused by the difference in diffusion rate of the elements between B2 phase and FCC phase in the eutectic high entropy alloy, generated in the diffusion zone and increased the shear strength of joints. The width of newly generated FCC' phase layer in front of the original FCC phase was wider than that in front of the B2 phase. The shear strength of the resultant joints increased and the fracture mode transformed from brittle fracture to ductile fracture with bonding temperature increasing. The maximum shear strength of 528 MPa was obtained and the dimples on fracture surfaces were found at the bonding temperature of 1050 °C.