Manufacturing of Complex NiTi Geometries with LPBF and Adapted Scanning Strategies

Abstract A binary Nickel-Titanium shape memory alloy was processed by Laser Powder Bed Fusion (LPBF) to manufacture lattice structures. The chemical composition of the powder was Ni 50.9 Ti 49.1 (at%) with the aim of obtaining pseudoelastic properties in the printed part. Adapted scanning strategies were chosen and used on a standard LPBF machine to achieve complex geometries with small, uniform feature sizes and a more precise modification of the local energy input. The as-built structures were analyzed with optical, thermal, and mechanical methods by means of optical microscopy, differential scanning calorimetry, and compression tests. The results demonstrate that LPBF combined with adapted scanning strategies can generate complex and homogeneous NiTi geometries (like metamaterials and programmable materials). Furthermore, the results show that scanning strategies have a significant influence on the thermal and therefore mechanical properties of the structures. We conclude that adapted scan strategies overcome the limitations of ordinary contour-hatch scan strategies and lead to shape memory properties which cannot be realized with conventional manufacturing techniques.