Abstract: Due to the complex underlying deformation mechanisms, understanding the synergistic mechanical effects of heterostructured multi-principal element alloy (MPEA) remains challenging. We developed a novel MPEA that integrates multiscale heterostructures with both bimodal grain sizes and precipitate sizes via asynchronous rolling, annealing, and subsequent aging treatment. Under tensile testing, an unexpectedly high density of stacking faults, Lomer-Cottrell locks, and deformation twins was activated, resulting in ultrahigh yield strength of 1290 ± 10 MPa, ultimate tensile strength of 1560 ± 15 MPa, and good ductility of 21 % ± 1 %. During the tensile deformation, the rotation angle of the grains at the heterogeneous interface reached up to 7.3° (shifted from 19.4° to 26.7° towards [111]), indicating that grain rotation occurred during the deformation. This effectively alleviated the stress concentration during the deformation, reduced crack propagation, and enhanced the work hardening ability. Consequently, the MPEA exhibited a superior strength-ductility combination. This perspective provides a novel strategy for designing new alloys and is conducive to understanding the coordinated deformation mechanisms of heterostructured MPEA.

Key words: Heterostructure, Strength-ductility synergy, Nano-precipitates, Grain rotation