Enhanced energy absorption in metamaterials fabricated from additively manufactured titanium alloy with superior strain hardening

Metamaterials with high energy-absorption capability are of great interest for crashworthy and protective applications. While titanium alloys offer an attractive combination of low density and high strength, most architected Ti metamaterials are fabricated from Ti-6Al-4 V (Ti-64), whose limited strain-hardening behaviour restricts their ability to dissipate energy. To overcome this limitation, this work introduces a novel approach that leverages Ti-6Al-2Sn-4Zr-6Mo (Ti-6246), a high-strength titanium alloy with exceptional strain-hardening characteristics, to enhance the performance of additively manufactured metamaterials. Sheet-based Gyroid and strut-based body-centred cubic (BCC) architectures were fabricated using Ti-6246 and benchmarked against counterparts made from Ti-64. Both Ti-6246 metamaterials exhibited substantially higher specific energy absorption (SEA), with the Ti-6246 Gyroid achieving the highest SEA of 47 kJ/kg, representing a 161% increase relative to the Ti-6246 BCC and a ∼ 47% increase relative to the Ti-64 Gyroid. This superior performance arises from the strong synergy between Ti-6246′s significant strain hardening and the Gyroid’s continuous surface geometry, which together suppress stress localisation and promote stable, progressive collapse, consistent with finite element predictions. These findings demonstrate the significant potential of pairing high strain-hardening alloys with stress-redistributing architectures to create next-generation lightweight, impact-resistant metamaterials.