Deformation-softening in ultrafine-grained materials

Plastic deformation is conventionally considered as a route for strengthening of metallic materials. During plastic straining, different crystal defects, such as dislocations, stacking faults and grain boundaries form, hardening the material. On the other hand, plastic deformation may also cause unexpected softening in ultrafine-grained and nanocrystalline materials. This paper summarizes the existing knowledge on this deformation-softening effect.