Generation of NiTi-SMA-micro parts using two step laser sintering

Due to special properties like superelasticity and reversible temperature induced deformation shape memory materials offer a unique potential in various fields of application. In medical engineering the shape memory effect, e.g. of NiTi alloys, realized on human body temperature, is in focus. Whilst the application of NiTi based products in cardiology is the most-known one, shape memory alloys can be found nowadays in trauma and reconstructive surgery as well. Surgeons demand for micro grippers to design active micro catheters for cerebric surgery. Furthermore, it is the idea to create NiTi micro actors for the directed stimulation of nerves. Because of its material properties resulting in adverse machinability, there are no machining methods for the production of NiTi micro parts. The generation of micro scale NiTi samples using two step laser sintering could recently be achieved at Laser Zentrum Hannover. As base material, spherical NiTi powders are used. The laser beam source is a 50 W fibre laser. Varying the compression of the powder bed as well as process parameters, micro parts of different density with a minimal width of <100 µm could be generated. Thereby, the special material properties are preserved: The sintered structures show the one way shape memory effect.