Additive manufacturing of SMA

In recent years, nickel-titanium (NiTi) has proven to be the most commercially successful shape memory material. It combines good performance with high functional fatigue strength. More than 95% of the systems available on the market use this alloy system. Thermo-mechanical optimization of shape memory elements often results in very complex structures. For this reason, and due to the difficulties in using conventional forming processes (including high strength and ductility), the use of additive processes is particularly interesting and innovative here, as it allows for functional consolidation with maximum design freedom.

The additive manufacturing of NiTi-based alloys using laser beam melting (PBF-LB/M) has already been scientifically investigated, and parameter windows for the successful production of geometrically complex structures have been identified. However, very specific process conditions occur during the laser melting process, such as very high cooling rates from the melt. As a result, the process forms a microstructure that not only differs greatly from conventionally manufactured materials, but also exhibits different grain sizes, inhomogeneities, and internal stresses. This affects the functional and mechanical properties as well as the thermal transformation behavior.

The objective of the work is to jointly investigate the complexity of materials and technology. By analyzing and considering all individual process steps along the value chain, a holistic understanding of the technology from melt to product is created. Only then is it possible to achieve economical, flexible, and customized production of complex SMA components.