Influence of heat treatment on corrosion resistance of NiTi shape memory alloys in NaCl solution

Abstract

This study conducts quenching heat treatment on hot-rolled Nickel-Titanium (NiTi) shape memory alloys, and explores effects of quenching heat treatment on microstructure and corrosion resistance of NiTi shape memory alloys through microstructure, cyclic tensile mechanical properties, polarization curves, electrochemical impedance spectroscopy, and Mott-Schottky tests. It reveals that quenching heat treatment refines the alloy's grain structure, enhances the uniformity of the microstructure, facilitates the diffusion and dissolution of Ti-C carbides, and optimizes the distribution of the alloy's chemical composition. While heat treatment may result in a reduction of the material's super-elasticity, it significantly enhances its corrosion resistance. It reduces the self-corrosion current density and corrosion rate, increases the charge transfer resistance, decreases the carrier concentration, and strengthens the stability of the passivation film. Consequently, quenching heat treatment proves to be an effective method for optimizing the performance of NiTi shape memory alloys and enhancing their corrosion resistance.