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

Area of Science:

• Materials Science
• Mechanical Engineering
• Impact Physics

Background:

• Research on mechanical metamaterials primarily focuses on quasi-static properties.
• Their behavior under extreme dynamic conditions and at macroscales remains largely unexplored.
• There is a need for advanced materials for impact mitigation in structural and defense applications.

Purpose of the Study:

• To develop a strategy for extreme impact mitigation at the macroscale.
• To investigate the dynamic behavior of novel metamaterials combining architecture and alloy design.
• To explore the potential of these materials for structural and defense applications.

Main Methods:

• Designing a shell-based microarchitecture for mechanical metamaterials.
• Utilizing an additively manufactured medium-entropy alloy (MEA) with low stacking fault energy (SFE).
• Analyzing the amplification of dynamic stress and activation of toughening mechanisms within the alloy.

Main Results:

• The shell-based architecture effectively amplifies dynamic stress compared to truss-based designs.
• Low SFE in the MEA facilitates diverse defect evolution and prolonged strain hardening.
• The developed metamaterial demonstrates effective impact mitigation across seven orders of magnitude in strain rate.

Conclusions:

• A novel strategy for macroscale impact mitigation using mechanical metamaterials has been established.
• The combination of shell-based architecture and low SFE MEA enables superior dynamic performance.
• These findings provide a foundation for developing scalable, lightweight, impact-resistant metamaterials.