Phase transformation and corrosion properties of surface oxidized NiTi shape memory alloy

Abstract

Oxide film was obtained on a NiTi shape memory alloy by a chemical method. The influences of surface oxidation on the phase transformations and corrosion resistance were assessed. Light blue oxide film formed on the alloy was mainly composed of TiO2. Differential scanning calorimetry(DSC) measurement displayed that the phase transformations was not affected by surface oxidation. Electrochemical tests indicated that the oxidized NiTi alloy showed better corrosion resistance than the non-oxidized one in the simulated body fluid. Scanning Electron Microscopy (SEM) revealed that lower pitting corrosion occurred for the oxidized NiTi alloy compared with the non-oxidized. The oxidized samples did not show any surface alterations except very small and homogeneously distributed pits were observed. © 2011 The Hard Tissue Biology Network Association.