Nitinol is the most widely researched and commercially available shape memory alloy (SMA) and has gained great attention in recent years. In addition to its unique and superior shape memory properties, its high strength, good biocompatibility and corrosion resistance have enabled its application in many fields such as biomedicine and aerospace. However, traditional machining of NiTi is troublesome and difficult to produce complex geometries. Additive manufacturing, on the other hand, not only has the capability for fabricating complex geometries, but also has the potential of altering the Ni/Ti ratio through preferential evaporation of Ni and thus tailoring the transformation temperature and therefore the shape memory properties.

Two compositions of NiTi SMA were manufactured by Laser Powder Bed Fusion (LPBF) Ni50Ti50 (shape memory effect, SME) and Ni51Ti49 (superelasticity, SE). Different processing parameters and heat treatments were conducted on each composition. The relationship between processing conditions, microstructure and mechanical properties (shape memory properties) was carefully analysed by means of X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and electron-backscatter diffraction as well as transmission electron microscopy. In addition, the mechanical properties and the shape memory properties were ascertained by means of tensile and compression tests. These results were used to ascertain the influence of processing parameters and heat treatments on the shape memory properties for both SME and SE nitinol alloys manufactured by LPBF.