Theoretical investigation of the interaction of oxygen with pure and K-doped NiTi shape memory alloys
نویسنده
چکیده
TiNi alloys are known as good biomaterials for medical applications since they exhibit compatibility with body tissue [1]. However, the possible release of Ni atoms to the body is a typical side effect where it can cause hazards to the operating system. The general interest here is thus to avoid the adverse effect by minimizing the existence of Ni atoms at the biomaterial surface layer. We have used two approaches on the process of the investigation. First, the pure surface is exposed to oxygen. Second, some of the surface Ni atoms are substituted by K atoms and then oxygen is exposed to the surface. The results show that Ti atoms are pulled outward and Ni atoms are pushed inward as a result of the oxygen adsorption. Different Ti oxides are consequently formed on the surface based on the coverage of oxygen adsorbed. At least 1 ML of O2 is required for the formation of a TiO2 protective layer. In both approaches of the study, the austenite (B2) and martensite (B19’) phases are considered and the electronic structures are analyzed based on density functional theory (DFT).
منابع مشابه
Theoretical investigation of the interaction of oxygen with pure and K-doped NiTi shape memory surface alloys
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