Functional and Mechanical Behavior of Ultra-Thin, Porous NiTi Fabricated via Laser Powder Bed Fusion

NitinolNitinol shape memory alloysShape memory alloys are used in a wide range of biomedical applicationsBiomedical applications because of their biocompatibilityBiocompatibility, shape memory and superelasticity properties, and high corrosionCorrosion resistance. Processing NiTi using additive manufacturingAdditive manufacturing (AM) has led to even wider possibilities for use in the biomedicalBiomedical field. The focus of the study was on producing ultra-thin (±500 um strutStruts), porous nitinolNitinol (NiTi) structuresStructure with varying levels of porosityPorosity using laser powder bed fusionLaser powder bed fusion (LPBF). Their functional and mechanical response was characterized. The effect of increased engineered porosityPorosity shifted the transformation temperaturesTransformation temperature higher and widened the hysteresis. As the amount of porosityPorosity increased, the compressive strengthCompressive strength decreased as did the elastic modulusModulus. The size and geometry of latticeLattices unit cells were found to have a significant effect on the mechanical response of these porous structuresPorous structures. All the porous structuresPorous structures had an elastic modulusModulus below 20 GPa. This low stiffness makes porous nitinolNitinol promising candidates for biomedicalBiomedical implants.