Superplastic Deformation of Cast Sn-Bi Alloy Lattice Structures Using Additively Manufactured Resin Molds

Metallic lattice structures are focused on as an excellent energy absorbing material. Their energy absorption property strongly depends on the ductility of the base material as well as the cell structure. The present study proposes new metallic lattice structures made of superplastic alloy. Sn-Bi eutectic alloy which shows typical room-temperature superplasticity was used for the base material. Lattice structures with the porosities of 72-75% were successfully manufactured through precision casting process. The resin mold was additively manufactured using a vat photopolymerization apparatus. Compression tests were carried out with different compression speeds. The Sn-Bi alloy lattice structures showed relatively high strain rate sensitivity exponent at low strain rate region. High energy absorption property was achieved at low strain rate region. Experimental results indicate that the superplastic deformation of the base material is effective to increase the energy absorption property of lattice structures.