Co-existence of nanoprecipitates with solute nitrogen evades the strength-ductility trade-off in metastable high entropy alloy

N and Ti co-doped Fe45Mn35Co10Cr10 alloys were prepared by Laser-Directed Energy Deposition (L-DED). We find that precipitate reinforcement of TiN particles introduced by harnessing N solid solution can result in a microstructure featuring attached MnO and TiN composite nanoparticles. Co-doped samples exhibit a notable 69% increase in yield strength compared with that of the free-doped, rising from 310 MPa to 533 MPa, maintaining 44.5% elongation. Even at 77 K, the co-doped alloy displays ultra-high strength, approximately 1400 MPa. These findings on metastable high entropy alloys through additive manufacturing open new avenues for their application in various fields.