Simultaneous Improvement of Ductility and Corrosion Resistance for a L1₂‐Strengthened High‐Entropy Alloy Achieved by Binder Jet 3D Printing and Aging

There are few studies to report the high‐entropy alloys (HEAs) fabricated by binder jet 3D printing (BJ3DP), and the simultaneous enhancement of ductility and corrosion resistance in L1 2 ‐strengthened HEAs prepared by BJ3DP remains unclear. In this study, a nonequiatomic Ni 27.7 Cr 24 Co 23.5 Fe 15.7 Mo 1.6 Al 3 Ti 4.5 (at.%) HEA is fabricated using BJ3DP followed by sintering and aging. Green samples are first prepared using optimized parameters: 50 μm layer thickness, 50% binder saturation, and 3 mm s −1 roller speed. After sintering at 1290 °C for 4 h, the samples show an equiaxed FCC matrix containing ≈98 nm spherical L1 2 precipitates together with intergranular sigma and L1 2 phases. Homogenization (1120 °C/2 h) and aging (700 °C/4 h) remove grain boundary phases and refine intragranular L1 2 precipitates to ≈8 nm. This microstructural optimization enhances ductility (elongation from ≈12.7% to ≈22.1%) while maintaining high strength (σ 0.2 ≈664 MPa, σ UTS ≈987 MPa). Corrosion resistance is also improved, as indicated by the decrease in corrosion current density from ≈220 nA cm −2 to ≈101 nA cm −2 . The improved performance is attributed to reduced galvanic corrosion caused by the elimination of harmful intergranular phases and the uniform distribution of finer precipitates. These results provide a viable strategy for tailoring mechanical and corrosion properties in additively manufactured HEAs.