Effect of Heat Treatments on Microstructure and Mechanical Properties of Nitinol Prototype Stents Produced by Laser Powder Bed Fusion

Abstract

Laser Powder Bed Fusion (L-PBF) is turning out to be very promising for biomedical components production and stents are among the devices that would be suitable for tailor-made production. One of the most common stent types are the self-expandable, manufactured with Nitinol (NiTi). The use of NiTi alloy with L-PBF needs to be well controlled, as Ni evaporation during the process leads to significant variations in the final component properties. In the present work, prototype NiTi stents were produced via L-PBF and heat treated to examine the possibility of employing this technology for their application, also considering the Ni evaporation resulting from the layer-by-layer deposition. Samples were characterized through differential scanning calorimetry (DSC), microstructural observations, and compression tests in plate-to-plate configuration according to the standard. In parallel, a commercially available stent manufactured with traditional technology was tested for comparison.