Achieving high strength and sufficient ductility in FeNiCoAlCrB high-entropy alloy by cryogenic rolling

This work proposes a novel strategy for a Fe 34.95 Ni 28 Co 17.5 Al 11.5 Cr 8 B 0.05 high-entropy alloy, achieving an exceptional strength-ductility synergy. The unique microstructure, fabricated via cryogenic rolling and intermediate-temperature annealing, features a bimodal distribution of ultrafine recrystallized face-centered cubic (FCC) grains (∼500 nm) and hard NiAl particles (∼300 nm), interlaced with pre-existing deformation and annealing twins. This architectured material demonstrates outstanding tensile properties, with a representative sample showing a high yield strength of 1.1 GPa and a sound tensile ductility of 28.2%. Deformation mechanism analysis reveals that initial strengthening is governed by the heterostructure, while a remarkable secondary work-hardening stage is driven by the dynamic formation of deformation twins and the 9R phase within the FCC matrix. Our work demonstrates a combinational microstructure engineering technique for enhanced mechanical properties in high entropy alloys.