Mechanical properties of CoCrFeMnNi high entropy alloy lattice structures formed by selective laser melting

Abstract

The special structure of the lattice structure makes it have many excellent properties. CoCrFeMnNi high-entropy alloys (HEAs) is widely used due to its good plasticity, low temperature strength and other advantages. To enhance the mechanical properties of the lattice structure, a unique decahedral internal diamond (DID) unit cell type was designed to construct the periodic lattice structure. The DID lattice structure was prepared by SLM using CoCrFeMnNi HEAs spherical powder as the material, and its surface morphology was observed under SEM. In comparison to conventional lattice structures, various lattice structures’ mechanical properties and deformation behaviors were analyzed using quasi-static compression tests and finite element analysis. Additionally, the effects of different rod diameter on the compressive performance and energy absorption characteristics of the DID lattice structure were also studied. The results show that the lattice structure prepared by SLM has good forming quality. In the tested samples, the DID structure has better bearing capacity and energy absorption performance, and the yield strength of the DID lattice structure with an overall size of 15 mm × 15 mm × 15 mm and a relative density of 25 % is 66 MPa, and the Young’s modulus is 3798 MPa. In addition, increasing the rod diameter can reduce the forming defects of the crossbar and further improve the compressive performance and energy absorption characteristics of the DID structure. This study provides a theoretical reference for the design and fabrication of load-absorber integrated structures, and confirms that the CoCrFeMnNi HEAs DID lattice structure can be used for lightweight support manufacturing applications.

Keywords

• Lattice structure
• Additive manufacturing
• Selective laser melting
• CoCrFeMnNi
• Mechanical property