Strain-bearing capacity and strain hardening awakened by inter-zone constraint in twin-structured Al0.1CoCrFeNi alloy

Abstract

Twin networks endow structural metallic materials with unprecedented mechanical properties. However, the understanding of how to utilize the maximum mechanical potential of twin structures remains limited, thus hindering the full performance of twin networks. In this work, the twin networks are embedded within fine grains (FGs) in Al_0.1CoCrFeNi alloy to awaken the strain-bearing capacity and strain hardening of twin networks. The experimental results show that the inter‑zone deformation incompatibility generates strong FG constraints that suppress early strain localization in the twin networks, raising the uniform elongation from 3 ± 0.5 % to 27 ± 3 %. Molecular dynamics simulations further verify that the intrinsic deformation mechanism of twin networks changes from necklace-like dislocations to hairpin-like dislocations under inter‑zone constraints. The strain hardening originates not only from the hetero-deformation induced strengthening and hardening, but also from the awakened strain-bearing capacity of twin networks, where the twin networks contribute ∼15 % hardening. These findings highlight the potential for enhancing the strengthening and hardening effects of twin networks by introducing extra constraint effect.