Local chemical ordering-mediated precipitation enables strength-ductility synergy in compositionally complex alloy at intermediate temperatures

When compositionally complex alloys (CCAs) with the face-centered cubic (fcc) structure are subjected to stress load at high temperatures, nanoclusters tend to form at grain boundaries, leading to intergranular fracture and limiting their applications. While the precipitation of elements which are prone to precipitate can alleviate this issue to some extent, it still leads to coarse precipitation at grain boundaries that deteriorates ductility. Herein, we propose a novel strategy to address this dilemma in a FeMnCoCrCuC CCA, i.e., cold rolling first introduces dense lath-like local chemical ordering (LCO) domains, which then acts as nucleation sites for high-density submicron-scale M₂₃C₆ precipitates inside grains during the subsequent aging. This LCO-mediated precipitation not only refines the precipitate size to ~225 nm but also modifies the fracture mechanism from intergranular cracking to multi-site initiated crack, effectively delaying crack propagation. At 400℃, the alloy achieves a yield strength of 621 MPa (112% increase compared with the initial state) while retaining 30.3% uniform elongation, outperforming most reported fcc CCAs and steels at this temperature. This work reveals the mechanism of LCO-guided precipitation and its contribution to the strength-ductility synergy, offering a new pathway for designing high-performance structural materials for elevated-temperature service.