Achieving Superior Strength–Ductility Synergy in an L1 2 ‐Type Ni 3 Al‐Based High‐Entropy Aluminide via Architecting Hierarchical Heterostructure
Zheng Liu, Laiqi Zhang, Pengfei Zhao, Chao WangABSTRACT
Achieving excellent strength–ductility synergy remains a critical scientific challenge for ordered Ni 3 Al‐based intermetallic alloys. In this work, a hierarchical heterostructure was deliberately architected in a novel L1 2 ‐type Ni 3 Al‐based high‐entropy aluminide, (Ni 38.5 Co 38.5 Al 11.5 Ti 5 Cr 4.5 Ta 2 ) 99.7 B 0.1 C 0.2 (at%), through a simple and cost‐effective thermomechanical processing route. The heterostructure features recrystallized/deformed grains, multiscale L1 2 phase, and L1 2 /FCC interfaces. The resulting alloy achieves an excellent strength–ductility synergy, combining a yield strength of 1025 MPa and an ultimate tensile strength of 1612 MPa with a total elongation of 24.8%. The ultra‐high yield strength primarily originates from the synergistic contributions of precipitation strengthening, hetero‐deformation‐induced (HDI) strengthening, and dislocation strengthening. More importantly, the continuous network‐like FCC phase, annealing twins, stacking‐fault networks, local Lomer–Cottrell locks, and sustained HDI hardening collectively enhance the strain‐hardening capability, thereby delaying plastic instability and enabling superior strength–ductility synergy. These findings provide valuable guidance for designing ordered Ni 3 Al‐based intermetallic alloys with an exceptional combination of ultra‐high strength, ductility, and strain‐hardening capability.