Unveiling strength-ductility synergy in eutectic high-entropy alloys via directional solidification

• • Directional solidification of Al19Fe20Co20Ni41 EHEA refines interlamellar spacing and eliminates isolated B2 phases, leading to a herringbone-like lamellar architecture that enhances strength-ductility synergy compared to conventional casting. • • The tailored microstructure promotes slip continuity at interfaces, enabling coordinated dislocation motion and uniform distribution across multiple slip systems, which is critical for achieving high tensile ductility without compromising strength. • • Homogenized GND density and multi-stage strain-hardening behavior, induced by sequential dislocation activation, are key micro-mechanisms contributing to the alloy's superior mechanical performance. • • The DS EHEA outperforms most reported thermomechanically processed and directionally solidified HEAs, demonstrating the efficacy of solidification path programming for microstructural design in extreme service environments.