Characterization of Nitrided/Oxidized Layers Covering Ni-Ti Shape Memory Alloy
In order to increase corrosion resistance, the NiTi shape memory alloy was covered by protection layers using glow discharge method. Samples were nitrided with some oxygen addition at temperatures: 350, 380, 400 and 800°C. Microstructure and sequence of obtained layers were studied applying X-ray diffraction technique as well as electron microscopy. Low temperature process produces a layers which consist of Ti3O5, TiN and Ni2Ti4O. Intermediate Ni3Ti layer was between Ni2Ti4O and NiTi matrix. High temperature process forms TiO2 and TiN with interlayer Ti2Ni. Surface does not contain phase with Ni, which is considered as toxic element.
Danuta Stróż & Małgorzata Karolus
T. Goryczka et al., "Characterization of Nitrided/Oxidized Layers Covering Ni-Ti Shape Memory Alloy", Solid State Phenomena, Vol. 130, pp. 151-154, 2007