Fig. 1. SEM morphology and particle size distribution of Ti-6Al-4V powder. (a) Powder morphology; (b) powder size distribution;

Fig. 2. Three-dimensional model of BCC lattice structures. (a) BCC gradient cell is transitioned continuously at the junction; (b) ZL-BCC-A; (c) ZL-BCC-B; (d) ZL-BCC-C; (e) ZC-BCC; (f) HD-BCC

Fig. 3. Three-dimensional model of FCC lattice structures. (a) FCC gradient cell is transitioned continuously at the junction; (b) ZL-FCC-A; (c) ZL-FCC-B; (d) ZL-FCC-C; (e) ZC-FCC; (f) HD-FCC

Fig. 4. Forming simulation of linear gradient lattice structures. (a) Forming stress in BCC structure; (b) deformation in BCC structure along forming direction; (c) forming stress in FCC structure; (d) deformation in FCC structure along forming direction

Fig. 5. SLM formed gradient lattice structures. (a) BCC-XY plane; (b) FCC-XY plane; (c) BCC-XZ plane; (d) FCC-XZ plane

Fig. 6. Microstructures at lattice beam. (a)‒(b) Microstructures of cross section; (c)‒(d) microstructures of longitudinal section

Fig. 7. EBSD orientation diagrams at lattice node (IPF: inverse pole figure). (a) IPF-X; (b) IPF-Y; (c) IPF-Z; (d) reconstruction of β-phase IPF-Z

Fig. 8. EBSD orientation diagrams at the lattice beam. (a) IPF-X; (b) IPF-Y; (c) IPF-Z; (d) reconstruction of β-phase IPF-Z

Fig. 9. Lattice structure defects. (a) Surface coated with powder; (b) unmelted powder; (c) lack of fusion; (d) hole

Fig. 10. Micro-CT analysis showing relative density of the lattice structure. (a) X-Z plane; (b) X-Y plane; (c) defect distribution

Fig. 11. Stress-strain curves of gradient lattice structures. (a) BCC structures; (b) FCC structures

Fig. 12. Static compression macroscopic morphology. (a) HD-BCC-∅1; (b) ZL-BCC-A; (c) ZL-BCC-B; (d) ZL-BCC-C; (e) ZC-BCC; (f) HD-FCC-∅1; (g) ZL-FCC-A; (h) ZL-FCC-B; (i) ZL-FCC-C; (j) ZC-FCC

Fig. 13. Force analysis and numerical simulation of BCC lattice structures. (a)‒(c) Force analysis of cell unit; (d) ZL-BCC-A numerical simulation; (e)‒(f) HD-BCC-∅1 numerical simulation; (g)‒(h) ZL-BCC-C numerical simulation

Fig. 14. Force analysis and numerical simulation of FCC lattice structures. (a)‒(b) Force analysis of cell unit; (c) ZL-FCC-A numerical simulation; (d)‒(e) HD-FCC-∅1 numerical simulation; (f)‒(g) ZL-FCC-C numerical simulation

Fig. 15. Young's modulus of the cell units with different rod diameters

Fig. 16. Energy absorption curves of BCC and FCC structures. (a) BCC structures; (b) FCC structures

Fig. 17. Energy absorption efficiency curves of BCC and FCC structures. (a) BCC structures; (b) FCC structures