Abstract:In this study, the BCC lattice structure (CAD-based and TPMS-based) of NiTi memory alloy with different volume fraction were fabricated by selective laser melting. The compression response before failure was analyzed. The effects of volume fraction, unit configuration and microstructure on energy absorption were studied. The results show that the NiTi BCC structure (volume fraction 5 %~25 %) has excellent specific energy absorption (0.45~1.89 J/g) before compressing to damage, and can recover to more than 92% of the initial height after heating. Volume fraction and unit configuration have an important influence on the compression response of NiTi alloy BCC lattice structure. When the volume fraction is less than 15 %, the traditional CAD sample has longer compressible strain and better specific energy absorption than the TPMS sample. When the volume fraction is greater than 15 %, the TPMS sample has higher compressive stress and better specific energy absorption than the CAD sample. The ladder effect in the SLM process leads to different material microstructures on the lower surface and inside of the lattice structure, the molten pool streaks at the lower surface is deeper and wider, and the grains are larger. The heterogeneity of the material leads to relatively poor mechanical properties, which is not conducive to energy absorption. Due to the different stress concentration locations and heterogeneous ratios, material heterogeneity has a greater adverse effect on low volume fraction TPMS samples.