Brazing of Inconel 600 Using Co₁₀Cr₈Cu₂₀Fe₆Mn₂₇Ni₂₉ Filler: An Experimental Approach

This study focused on the development and performance of a novel high-entropy alloy (HEA) brazing filler metal for the assembly of nickel-superalloy components, aiming to address the limitations of traditional nickel-based brazing filler metals. Co₁₀Cr₈Cu₂₀Fe₆Mn₂₇Ni₂₉, the composition of the HEA filler metal, was chosen considering brazing Ni-base Alloy 600 because of its face-centered cubic (FCC) crystalline structure and suitable melting temperature. The synthesis of filler was conducted using wet mechanical alloying method to prevent oxidation; after 60 h, the process resulted in a crystallite size of 66.19 nm and a lattice strain of 0.01%. Wettability testing on Alloy 600 indicated that the optimal brazing temperature was 1180°C, at which point the HEA filler metal showed excellent spreading behavior, characterized by a low wetting angle of 14°. The maximum shear strength achieved was 290 MPa with a hydrogen atmosphere brazing and a 90 min hold time. However, fine-scale porosity and oxide inclusions at the grain boundaries, after this duration, were identified as the primary reasons for the decrease in shear strength, which increased the risk of brittle fracture. While fine-scale porosity and oxide inclusions were found as possible reasons affecting overall ductility, fractographic study indicated significant microvoid coalescence in the HEA joints.