Properties of a superelastic NiTi shape memory alloy using laser powder bed fusion and adaptive scanning strategies

Abstract

A NiTi shape memory alloy with the nominal composition Ni50.9Ti49.1 (at%) was processed by laser beam melting/laser powder bed fusion and the process parameters as well as the type of scanning strategy (point-like exposure) were optimized in a first step to obtain delicate lattice structures (strut diameters below 200 µm). In the second step, the lattice structures were analyzed by means of optical and electron microscopy as well as computer tomography to obtain the interrelation between the process parameters, strut diameter and the uniformity of the corresponding struts. The processing, especially the laser power and the type of point-like exposure, has a strong influence on the resulting strut diameter and, therefore, on the haptic stiffness of lattice structures and the mechanical properties (deformability, superelasticity). Unlike other approaches, our findings imply that filigree NiTi lattices with high uniformity can be manufactured on a standard industry laser powder bed fusion machine without modifying its hard- or software configuration.