Rotating bending fatigue response of laser processed porous NiTi alloy

Porous implants are known to promote cell adhesion and have low elastic modulus, a combination that can significantly increase the life of an implant. However, porosity can significantly reduce the fatigue life of porous implants. Very little work has been reported on the fatigue behavior of bulk porous metals, specifically on porous nitinol (NiTi) alloy. In this article, we report high-cycle rotating bending fatigue response of porous NiTi alloys fabricated using Laser Engineered Net Shaping (LENS™). Samples were characterized in terms of monotonic mechanical properties and microstructural features. Rotating bending fatigue results showed that the presence of 10% porosity in NiTi alloys can decrease the actual fatigue failure stress, at 106 cycles, up to 54% and single reversal failure stress by ~ 30%. From fractographic analysis, it is clear that the effect of surface porosity dominates the rotating bending fatigue failure of porous NiTi samples.