Corrosion behaviour of the NiTiX (X = Si, Mg, Al) alloy prepared by self-propagating high-temperature synthesis

The NiTi alloys are used in the biomaterial field, because of their shape memory, superelasticity, and good corrosion resistance. The influence of alloying elements on the corrosion behaviour of NiTi was studied in this research. Samples were made by the self-propagating high-temperature synthesis method, milled, and then sintered by the spark plasma sintering method. Si, Mg, and Al were used as alloying elements always in 5 wt.%. Studied materials were compared with reference cast NiTi. Polarization resistance was measured after 1 and 12 hours of stabilization in phosphate-buffered saline. It was found out that alloying elements do not have a clear effect on polarization resistance. Si increased Rp and on the other hand, Al decreased it. Measurement of cyclic potentiodynamic polarization in PBS was conducted, too. All studied samples showed signs of localized corrosion. Corrosion was probably initiated in pores, which are presented on the surface due to used manufacturing technology.