Characterization of a NiTi SMA wire treated by nitrogen plasma based ion implantation (PBII)

Abstract

NiTi SMA wire with Ni-free surface is desirable as construction materials for a range of biomaterials to actuators associated to shape memory and superelastic properties. In biomaterials a potential problem with NiTi implant devices is the release of Ni in the human body. This work analyzes the effects of nitrogen plasma based ion implantation (PBII) technique in a wire of NiTi with shape memory effect associated to a Ni-free surface. The samples were treated for 60 min at 741 °C, with 16 kV high voltage pulses. Results of the thermo-mechanical properties of the PBII treated samples showed that there is no effect of the PBII treatment on the shape memory effect when compared to NiTi samples with no PBII treatment, which is desirable for applications addressing Ni-free surface and shape memory effect. Although it was noted that the stress-strain test causes cracks perpendicular to the stress direction on the treated surface.