Achieving high strength and ductility in VCoNi medium-entropy alloy via wire and arc additive manufacturing with elemental wires

Abstract

Wire and arc additive manufacturing (WAAM), known for efficiently producing large-scale components, is predominantly applied to traditional alloys. However, the use of WAAM to fabricate high-entropy alloys and medium-entropy alloys (MEAs) remains less explored. This study demonstrates the successful fabrication of a VCoNi MEA with a relative density exceeding 99.9 % using elemental wires through WAAM. The fabricated VCoNi MEA exhibits a face-centered cubic structure with columnar grains aligned in the building direction, characterized by a high dislocation density, several stacking faults (SFs), and a high density of L12 domains within the grains. Notably, this VCoNi MEA achieves an ultimate tensile strength of 951.9 MPa, while maintaining an impressive tensile elongation of 35 % and superior strain-hardening capability. Microstructural analysis indicates that the synergy of dislocation network substructures, L12 domains and the activation of SFs and Lomer-Cottrell locks contributes to its high strain hardening capacity and excellent ductility. This work underscores the potential to produce near full-density components with superior mechanical performance using elemental wire, highlighting its significance for industrial applications.