Dissimilar joining of 6061 Al alloy and FeCoNiCrMn HEA by CMT arc welding-brazing: Microstructure and interfacial behaviour

6061 Al alloy was joined to FeCoNiCrMn high-entropy alloy by Cold Metal Transfer advanced arc welding-brazing with an Al filler. Increasing heat input from 55 to 139 J mm −1 improved wetting, increasing the wetting length from ∼1.8 to ∼4.6 mm and decreasing the wetting angle from ∼140° to ∼70°. A continuous bilayer reaction layer formed at the interface, consisting of an ultrafine layer adjacent to the high-entropy alloy and an irregular Fe–Al intermetallic layer near the weld metal. Fe 2 Al 5 and Fe 4 Al 13 were the dominant intermetallics, and multielement substitution caused lattice distortion and strain localisation. The maximum tensile-shear load reached ∼2.9 kN at a heat input of 139 J mm −1 . The improvement in joint load was accompanied by enhanced wetting and interfacial bonding, together with a transition of the dominant fracture path from the brazed interface toward the Al-side fusion boundary.