Exploiting multiscale dynamic toughening in multicomponent alloy metamaterials for extreme impact mitigation

Prof. Yang Lu's group recently published a article in Science Advances, which unveils a novel strategy for designing ultra-lightweight, impact-resistant metamaterials by combining triply periodic minimal surface (TPMS) architectures with a high-resolution selective laser melting (HR-SLM)-fabricated CoCrNi medium-entropy alloy (MEA). The key innovation lies in the synergistic interplay between the gyroid shell microstructure, which enhances dynamic stress amplification and uniform strain distribution, and the alloy’s low stacking fault energy (SFE), enabling multiscale toughening mechanisms like deformation twinning, dislocation networks, and nanoscale amorphization across strain rates spanning seven orders of magnitude. This design achieves unprecedented energy absorption, outperforming conventional lattices and monolithic metals in ballistic tests by arresting projectiles at velocities exceeding 900 m/s. The HR-SLM process further refines grain structures and dislocation densities, boosting strength-ductility synergy. With applications in aerospace, defense, and automotive sectors, this work pioneers scalable, architected materials for extreme impact mitigation, offering a roadmap for next-generation lightweight protective systems. The study bridges critical gaps in dynamic metamaterial design, emphasizing the role of architecture-material synergy in unlocking transformative mechanical properties. The research is published by ScienceAdvance on May 7, 2025.

Article in ScienceAdvance 

https://www.science.org/doi/full/10.1126/sciadv.adt0589

Abstract:

Mechanical metamaterials can unlock extreme properties by leveraging lightweight structural design principles and unique deformation mechanisms. However, research has predominantly focused on their quasi-static characteristics, leaving their behavior under extreme dynamic conditions, especially at length scales relevant to practical applications largely unexplored. Here, we present a strategy to achieve extreme impact mitigation at the macroscale by combining shell-based microarchitecture with an additively manufactured medium-entropy alloy (MEA) featuring low stacking fault energy (SFE). Notably, the shell-based architecture amplifies the effective dynamic stress within the metamaterial compared to truss-based morphologies, leading to the earlier activation of multiscale toughening mechanisms in the alloy. The low SFE of the MEA enables the evolution of a diverse array of defect types, thereby prolonging strain hardening behavior across seven orders of magnitude in strain rate. These fundamental insights could establish the groundwork for developing scalable, lightweight, impact-resistant metamaterials for structural and defense applications.