Segregation-dislocation self-organized structures ductilize a work-hardened medium entropy alloy
Bojing Guo, Dingcong Cui, Qingfeng Wu, Yuemin Ma, Daixiu Wei, L. S. R. Kumara, Yashan Zhang, Chenbo Xu, Zhijun Wang, Junjie Li, Xin Lin, Jincheng Wang, Xun‐Li Wang, Feng He
Abstract
Dislocations are the intrinsic origin of crystal plasticity. However, initial high-density dislocations in work-hardened materials are commonly asserted to be detrimental to ductility according to textbook strengthening theory. Inspired by the self-organized critical states of non-equilibrium complex systems in nature, we explored the mechanical response of an additively manufactured medium entropy alloy with segregation-dislocation self-organized structures (SD-SOS). We show here that when initial dislocations are in the form of SD-SOS, the textbook theory that dislocation hardening inevitably sacrifices ductility can be overturned. Our results reveal that the SD-SOS, in addition to providing dislocation sources by emitting dislocations and stacking faults, also dynamically interacts with gliding dislocations to generate sustainable Lomer-Cottrell locks and jogs for dislocation storage. The effective dislocation multiplication and storage capabilities lead to the continuous refinement of planar slip bands, resulting in high ductility in the work-hardened alloy produced by additive manufacturing. These findings set a precedent for optimizing the mechanical behavior of alloys via tuning dislocation configurations. Textbook theory asserts that dislocation hardening inherently sacrifices ductility. Here, the authors report that high-density dislocations with segregation-modified configurations produced by additive manufacturing increase strength without compromising ductility.