Superior compressive performance of CoCrNi-TiC octet plate-lattices metamaterials

High/Medium-entropy alloys with exceptional mechanical properties have recently emerged as advanced solutions for the design of new metamaterials. However, medium-entropy alloy (MEA), especially CoCrNi, doesn't have the desirable yield strength. In order to address this issue, the nano-TiC particles were utilized as reinforcement agents to enhance the mechanical performance of CoCrNi-based alloy metamaterials in this work. Compressive performance of the proposed metamaterial was investigated through experimental and numerical simulation methods. The experimental findings indicate that the incorporation of TiC significantly improves the mechanical properties of CoCrNi-based octet-plate metamaterials, Specifically, the strength and energy absorption of metamaterials with 3% TiC increase by 60% and 25%, respectively, compared to those of CoCrNi metamaterials. The failure mechanism exhibits an ideal layer-by-layer collapse mode, accompanied by localized buckling instabilities. Numerical results show that, as the fraction of TiC increases from 0% to 5%, the strength and energy absorption of metamaterials increase by 108% and 118%, respectively. Furthermore, comparing with the additively manufactured metamaterials with octet-plate/truss unit cells, CoCrNi-TiC metamaterials exhibit superior mechanical properties at the same relative density.