Enhancement of strength-ductility synergy by trace ¹¹B addition in 13Cr ODS steel

ODS steel typically shows high strength with low ductility, and the strength-ductility synergy is one of the major challenges concerning the application of ODS steel in fusion reactors. Here we developed a¹¹B-added 13Cr ODS steel with outstanding strength-ductility synergy via mechanical alloying and subsequent spark plasma sintering. ¹¹B isotope with low neutron absorption cross section was added into the 13Cr ODS steel that led to an improvement of total elongation by over 40 % at room temperature compared to the its ¹¹B-free counterpart. A combination of high UTS up to 887.3 MPa and total elongation of 21.7 % was obtained in ¹¹B-added 13Cr ODS steel. The atomic scale high-resolution characterization techniques including nano secondary ion mass spectrometry, atom probe tomography and transmission electron microscopy revealed that ¹¹B was concentrated within the interior of the nano-oxides, which played a key role in accommodating the strain gradient and sustaining a low strain-hardening rate during plastic deformation by the tunable pinning effect of ¹¹B-containing particles to dislocations. This work provides a simple yet substantially effective new pathway for designing ODS steel with superior strength-ductility synergy.