Synergistic Enhancement of Creep Performance in Al 19 Co 21 Fe 20 Ni 40 Eutectic High‐Entropy Alloy by Coupling Heterostructure Design With Boron‐Assisted Interfacial Optimization

ABSTRACT This study systematically investigates the creep behavior of an Al 19 Co 21 Fe 20 Ni 40 eutectic high‐entropy alloy (EHEA) at 500°C, focusing on the synergistic effects of heterostructure design and trace boron doping. Thermomechanical processing was employed to produce a heterostructure consisting of alternating lamellar and equiaxed regions. Creep tests reveal that this heterostructured alloy achieves a remarkable 320% increase in creep life compared to the as‐cast baseline. This enhancement originates from hetero‐deformation induced (HDI) strengthening, which drives the hard B2 phase to actively participate in co‐deformation alongside the FCC phase, effectively dispersing localized stress concentrations. Building on this heterostructure, the addition of 0.1 wt% boron further optimizes the FCC/B2 interfaces, yielding an additional 42% improvement in creep life. Geometric phase analysis demonstrates that boron strengthens the FCC/B2 interface, significantly reducing localized shear strain and stress concentration. This optimized interfacial state effectively suppresses the nucleation and growth of creep voids, delaying overall damage accumulation. These findings provide a practical strategy for developing advanced heat‐resistant EHEAs.