A 3D‐Printed SFE‐Graded Alloy Mitigates Cryogenic Discontinuous Plastic Flow and Hydrogen Embrittlement

ABSTRACT The lunar polar permanently shadowed regions, rich in water ice for hydrogen production, impose a trade‐off in FCC alloys: lowering stacking‐fault energy (SFE) enhances hydrogen embrittlement resistance but exacerbates cryogenic discontinuous plastic flow (DPF). To address this, we designed and fabricated via additive manufacturing a compositionally graded (CoCrMn) 100 − 2 x Fe x Ni x alloy with a single‐phase FCC structure. Guided by thermodynamic calculations and first‐principles predictions, the gradient‐structured build exhibits spatial SFE and microstructural gradients. Quasi‐static tensile tests from 298 K down to 20 K reveal significant strengthening with retained high ductility, while DPF is strongly suppressed, showing only minor stress drops. Mechanistically, the graded architecture partitions deformation: high‐SFE regions promote dislocation glide and cellular substructures, whereas low‐SFE regions enable planar slip and deformation nanotwinning, delocalizing strain and suppressing avalanche‐like dislocation activity. Under hydrogen charging at 298 K, embrittlement resistance is preserved via a dual mechanism combining deformation‐induced nanotwins and a Mn concentration gradient. This synergy balances dislocation mobility and hydrogen trapping, offering a new paradigm for simultaneous improvement of cryoplasticity and hydrogen compatibility. Our work establishes a multidisciplinary design strategy for alloys targeting extreme hydrogen and cryogenic environments.