Unveiling the mechanisms of strength-ductility synergy in an additively manufactured nanolamellar high-entropy alloy.

The combination of alloy design and advanced manufacturing techniques inspires solutions to critical engineering challenges, such as simultaneously achieving high strength and high ductility in structural alloys. Eutectic high-entropy alloys (EHEAs) are particularly promising for their integration of both strong and ductile phases. Here, using valence electron concentration as a criterion, we employ laser powder bed fusion (L-PBF) to fabricate Al19Co20Fe20Ni41 EHEA with a nanolamellar microstructure, chosen specifically for its increased fraction of ductile face-centred cubic phase. The EHEA processed by L-PBF demonstrates a combination of high yield strength exceeding 1.3 GPa and large uniform elongation of 20%. This strength-ductility synergy arises from the coherent nanoprecipitates, nanolamellar structures, hierarchical microstructure heterogeneity, and deformation-induced nanovoids activated within the hard body-centred cubic lamellae. This study provides a pathway for designing high-performance alloys by integrating multiple deformation mechanisms, offering opportunities for advanced structural material development.