Shape memory alloys own the property of to changing in a controlled way in response to an externally applied stimulus such as stress, temperature or magnetic field. Additive manufacturing of shape memory alloys is used to achieve unique properties, which cannot be realized by conventional manufacturing techniques. By manufacturing shape memory alloys with laser powder bed fusion (LPBF), the fabrication of complex 3D structures such as filigree lattice structures with programmable characteristics are possible. The requirement for the production of such programmable materials is the identification of a suitable process parameter window.

In this contribution, we present the additive manufacturing of NiTi lattice structures with programmable properties in the as-built condition. We show the potential of manufacturing uniform, filigree and superelastic structures on conventional LPBF-machines including bend, inclined struts with angles of inclination of 30 ° to the powder bed and a strut diameter of 200 µm. These filigree parts show the achievement of optimizing the digital workflow of adaptive scan strategies, which realize a higher freedom of geometry when producing lattice structures and a more precise replication of the digital model. By means of the selected laser parameters and scan strategy, the quality of the structure as well as the phase transformation temperatures and therefor the transformation stress levels are adjusted. As a result of the chosen unit cell designs and the superelasticity of NiTi, we show a metallic structures, which exhibits a leap in stiffness under compression load and elongations of 30 % without failure. This approach shows the potential for further improvement of LPBF-produced NiTi and the manufacturing and characterization methods of programmable materials.