Strength-ductility synergy in a non-equiatomic Co–Cr–Ni medium entropy alloy wall structure deposited using twin-wire arc additive manufacturing

Abstract

An innovative twin-wire arc additive manufacturing (T-WAAM) has been deployed to fabricate a Co-rich non-equiatomic Co–Cr–Ni medium entropy alloy. The TWAAM-built single-wall structures of Co50Cr10Ni40 alloy were fabricated under argon gas shielding using dual gas metal arc welding sources. The microstructure studies revealed a single-phase FCC crystal structure and defect-free deposition. The slender columnar substructure and cellular substructure are formed along the build direction (BD) and scan direction (SD) respectively, which are commonly observed in the wall structures of other conventional FCC alloys. The tensile coupon SD and BD displayed a superior high strength and ductility combination. The T-WAAM-fabricated Co50Cr10Ni40 alloy showed both strength and elongation 1.4 times greater than that of the laser additive manufactured equiatomic CoCrNi wall structure. Thus, the study opens up a new avenue to tailor the mechanical properties of CoCrNi MEA by composition variation, with an added advantage of higher deposition rates of TWAAM. © 2024 Elsevier B.V.