A high-strength self-propagating-brazed Al0.1CoCrFeNi joint at high temperatures with nano-multilayer foils composed of Ni/Al-Al-FeCo/CrNi filler metal

Novel nano-multilayer foils composed of Ni/Al-Al-FeCo/CrNi filler metals were developed for brazing Al0.1CoCrFeNi alloys. These Ni/Al-FeCo/CrNi filler metals, designed using a high-entropy concept, were integrated to increase the mixing entropy and form solid solution structures. This strategic integration was aimed at preventing the formation of intermetallic compounds. The microstructural evolution and shear strength of the brazed joints were investigated by varying the holding time and brazing temperature. The results demonstrated the formation of a defect-free brazing joint, marked by the emergence of a solid solution structure resulting from the higher mixing entropy. With increasing temperature, the contribution of the solid-solution phase to the strengthening effect on the joint was more significant. The maximum shear strengths of the brazed joints were 308.5 MPa and 292.8 MPa at room temperature and 800 °C, respectively. Furthermore, the extended holding time and increased brazing temperature produced a steady increase in the shear strength of the joint with a corresponding transformation in the fracture mechanism from cleavage to ductility. This study introduces a novel process for brazing Al0.1CoCrFeNi and offers a technological paradigm for manufacturing industry at a high temperature (800 °C). [Display omitted] •A novel brazing route for producing high-entropy alloy joints was proposed at lower temperatures which judiciously stacking three thin foils that differ in nature and functionality.•A full solid solution structure (AlCoCrFeNi)x HEAs fabricated from nano-multilayers.•The maximum shear strength of the joint is 292.8 MPa at 800 °C.•The joint formation mechanism was attributed to the high-entropy solution reactive occurring in the joint.