Hetero-lamellar design alleviates the Ubiquitous strength-ductility trade-off in high-entropy alloys

The strength-ductility trade-off remains a persistent challenge in high-entropy alloys (HEAs). In this work, we overcome this limitation through a novel microstructural design strategy by employing a simple, one-step directional solidification process to fabricate a heterogeneous lamellar structure in a non-eutectic Al_1.25CoCrFeNi_2.7W_0.3 HEA. This method, distinct from complex thermomechanical routes, enables the formation of well-aligned alternating soft (FCC) and hard (BCC) lamellae. This architecture simultaneously activates three synergistic mechanisms: (1) Sustained hetero-deformation induced (HDI) strengthening, elevating the ultimate tensile strength from 1178 MPa to 1321 MPa (a 12% improvement) while maintaining high strain hardening; (2) Improved overall ductility (17%, a 31% increase) partly attributed to the activation of multi-slip systems within the otherwise brittle BCC phase under hetero-deformation constraints; and (3) Improved damage tolerance through crack-tip blunting by the FCC phase, which effectively arrests microcrack propagation. Our findings demonstrate that multi-scale mechanical contrast engineering, achievable via straightforward processing, is key to transcending property limits in HEAs. This work provides a new pathway for designing high-performance heterostructured alloys.