AVS 47th International Symposium
    Material Characterization Tuesday Sessions
       Session MC-TuP

Paper MC-TuP20
Investigation of Oxide Layers Formed on NiTi Shape Memory Alloys at Elevatated Temperatures

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: R.G. Vitchev, Katholieke Universiteit Leuven, Belgium
Authors: R.G. Vitchev, Katholieke Universiteit Leuven, Belgium
G. Firstov, Katholieke Universiteit Leuven, Belgium
H. Kumar, Katholieke Universiteit Leuven, Belgium
Y. Liu, Nanyang Technological University, Singapore
B. Blanpain, Katholieke Universiteit Leuven, Belgium
J. Van Humbeeck, Katholieke Universiteit Leuven, Belgium
Correspondent: Click to Email
NiTi shape memory alloys have attracted considerable attention as materials for medical implants. It is known that the biocompatibility of the implants fabricated from NiTi depends on their surface composition since nickel often causes allergic and toxic effects. The purpose of this study is to characterise the thermally grown oxides on the surface of an NiTi alloy (50 at. % Ni). The samples were heat treated in air in the temperature range 473-1073 K. Thermo-gravimetry measurements were carried out to investigate the kinetics of oxidation. X-ray photoelectron spectroscopy and Auger electron spectroscopy combined with sputter depth profiling were used to investigate the surface composition and chemical state of the constituent atoms and their depth distribution. X-ray diffraction was used to determine the phases formed in the oxide layers. The influence of the surface treatment of the alloy on the oxidation process was also studied. Thermodynamic calculations were carried out to explain the oxidation behaviour of the NiTi alloy.