H. Meier, C. Haberland, J. Frenzel, Ruhr University Bochum, Bochum, Germany
Generally, manufacturing of Nickel-Titanium shape memory components is challenging because machining and elaborate thermomechanical treatments are by no means easy. Hence, we introduce Selective Laser Melting (SLM) as a novel powder metallurgical freeform technology for direct manufacturing of complex Nickel-Titanium devices. Due to the additive layer-based principle of the technique, high complex 3d structures can be realized which hardly can be manufactured by conventional processing methods. The present work describes the complete processing route for the near net shape fabrication of Nickel-Titanium by SLM including powder preparation. We investigate the influence of processing parameters and conditions on microstructural and functional properties of SLM-Nickel-Titanium. We present detailed results of material analyses carried out by using optical microscopy, scanning electron microscopy, x-ray diffraction and differential scanning calorimetry. It was found that selective laser melting results in slight compositional changes due to a small evaporation of Nickel and a slight pick up of Oxygen impurities. However, a careful control of process parameters allows keeping these effects at a minimum. Our results clearly show that SLM provides an attractive technology for the direct fabrication of Nickel-Titanium based SMA devices with complex structures.
Summary: We introduce Selective Laser Melting as a novel freeform technology for the direct manufacturing of Nickel-Titanium shape memory devices. We investigate the influence of the laser treatment and certain processing conditions on microstructural and functional properties. Our results clearly show that Selective Laser Melting provides an attractive technology for the direct fabrication of Nickel-Titanium based SMA components with complex 3d structures.
