Fig. 1. Design of body-centered tetragonal hollow lattice structure

Fig. 2. Morphology of NiTi pre-alloyed powder and LPBF forming of lattice structure. (a) SEM image of NiTi pre-alloyed powder; (b) LPBF forming process; (c) scanning strategy; (d) as-fabricated components

Fig. 3. Finite element simulation and uniaxial tensile curve. (a) Meshing and boundary conditions; (b) uniaxial tensile stress-strain curve with LPBF processed tensile sample shown in inset

Fig. 4. Forming quality of lattice structure fabricated by LPBF. Top view morphologies of (a) BCT-100, (b) BCT-93, (c) BCT-75, and (d) BCT-50; (e) measured external and internal diameter values of four lattice structures; (f) measured height values of four lattice structures; (g) schematic of staircase effect; (h) cross-sectional morphology of BCT-50 strut

Fig. 5. Phase composition, phase transition behavior and microstructure of BCT-100. (a) XRD pattern; (b) DSC curves of sample; (c) low-magnification SEM image of molten pool; (d) high-magnification SEM image of single molten pool

Fig. 6. Finite element simulation results of lattice structures. (a) Compression force-deformation rate curves; (b) stress distributions and deformation characteristics of BCT-100, BCT-93, BCT-75, and BCT-50 under deformation rates of 0.15 and 0.30

Fig. 7. Results of compression failure test of LPBF fabricated lattice structures. (a) Compression force-deformation rate curves；(b) first maximum compressive force and its corresponding compressive deformation rate; (c) specific energy absorption curves

Fig. 8. Dynamic process of lattice structures with different mass coefficients under different deformation rates during compression

Fig. 9. Compression cycle experimental curves and recovery rates of lattice structures. Force-deformation rate curves of (a) BCT-100, (b) BCT-93, (c) BCT-75, and (d) BCT-50 in five compression cycles; deformation rates recovered after unloading, deformation rates recovered by heating, and irreversible deformation rates of (e) BCT-100, (f) BCT-93, (g) BCT-75, and (h) BCT-50

Table 1. Compositions of NiTi pre-alloyed powder

Table 2. Material mechanical parameters of NiTi solid components prepared by LPBF