Lattice softening for producing ultrahigh strength of iron base nanocrystalline alloy

One can increase the strength of metallic materials by pinning dislocations with nanoscale obstacles, as the dislocations facilitate plastic deformation. However, simultaneous achievement of the ultrahigh strength and the ductility is extremely difficult in conventional metallic materials. Here we show that the ultrahigh strength iron base alloy with enhanced ductility, whose strength is approaching ideal strength and being twice as much as the upper limit of conventional alloys, can be realized by introducing the paradox concept of lattice softening. Designing atomic arrangement with specific electronic structure creates the lattice softening, and a nanograined structure is then produced by subsequent processing with severe plastic deformation.