Development of ultrahigh strength and high ductility in nanostructured iron alloys with lattice softening and nanotwins

Bulk nanostructured materials exhibit high strength but very low ductility. In this study, ductile nanostructured iron-base alloys are successfully developed using a combination of three strategies: appropriate choice of chemical compositions for lattice softening, severe plastic deformation using high-pressure torsion for grain refinement, and annealing for nanotwin formation. Accordingly, exceptional performance of both ultrahigh strength, 2.3–3 GPa, and high elongation to failure, 10–20%, which has never been reported for metallic materials, is achieved.