Atomic faulting induced exceptional cryogenic strain hardening in gradient cell–structured alloy

Abstract

Coarse-grained materials are widely accepted to display the highest strain hardening and the best tensile ductility. We experimentally report an attractive strain hardening rate throughout the deformation stage at 77 kelvin in a stable single-phase alloy with gradient dislocation cells, that even surpasses coarse-grained counterparts. Contrary to conventional understanding, the exceptional strain hardening arises from a distinctive dynamic structural refinement mechanism facilitated by the emission and motion of massive multi-orientational tiny stacking faults (planar defects), which are fundamentally distinct from the traditional linear dislocation mediated deformation. The dominance of atomic-scale planar deformation faulting in plastic deformation introduces a different approach for strengthening and hardening metallic materials, offering promising properties and potential applications.

Ultrastrong and ductile medium-entropy alloys via hierarchical ordering

“…S12C). The formation of nano-SF networks causes dynamic grain refinement, resulting in a reduction of dislocation mean free path and promoting dynamic Hall-Petch hardening ( 40 , 41 ). Even in the fractured RAA alloy, high-density intersecting SFs persist ( Fig.…”

Mechanomaterials and Nanomechanics: Toward Proactive Design of Material Properties and Functionalities

“…36 A direct-current electrodeposition technique was used to introduce controllable structural gradients in Cu (in both TB spacing and grain size) and show that the gradient nanostructured material defies the rule of mixtures in that it can achieve strength higher than that of the strongest component. 27 Recently, a gradient cell-structured multiprincipal element alloy was developed, in which atomic-scale planar deformation faulting, rather than the conventional linear dislocation, dominated the plastic deformation, leading to exceptional strain hardening behavior at 77 K. 37 The gradient induced additional strengthening and strain hardening, a concept of general significance that suggests a route to overcoming the strength−ductility trade-off by introducing structural gradients at different length scales.…”