Unit-level hardening-driven strengthening in gradient nanotwinned Cu

Abstract

Gradient nanotwinned (GNT) structures are a representative class of heterogeneous architectures that enhance the strength of metallic materials by introducing structural gradients. In this study, we show that both extra strengthening and work hardening in GNT Cu can be further improved by increasing the work hardening capacity of individual units, even with a constant structural gradient. Higher unit-level work hardening suppresses strain localization, facilitates more uniform gradient plastic deformation, and promotes the additional storage of geometrically necessary dislocations (GNDs) in formation of bundles of concentrated dislocations. These GNDs contribute significantly to the enhanced strengthening and hardening behavior of GNT Cu.