Synergistic strength and toughness through impact-induced nanostructural evolutions in metals

Synergistically improving strength and toughness is imperative to designing next generation materials for critical engineering applications. Incorporating structural heterogeneities at the nanoscale can synergistically improve the strength and toughness of metals through eliciting complementary deformation mechanisms. Here, we present a synergistic enhancement in strength and toughness in microscale samples with a gradient-nano-grained structure produced through impact-induced recrystallization of initially single-crystal defect-free silver microcubes. The impacted samples exhibit ultra-high strain hardening rates and up to 4.7x the yield strength and 5x the toughness as the single-crystal silver micropillars, and up to 7.4x the yield strength and 4x the toughness as bulk coarse-grained silver. Synergistic improvements in mechanical properties are achieved through the activation of intragranular dislocation slip and intergranular grain boundary rotation and migration enabled through inversely correlated gradients in grain size and dislocation density.