Aging-driven TiO2 oxide formation and its impact on the corrosion resistance of NiTi alloy developed by powder metallurgy

Purpose This study aims to investigate the effect of aging treatments on the microstructure and bio-corrosion behavior of NiTi shape memory alloy fabricated via powder metallurgy, aiming to optimize aging parameters for enhanced performance in biomedical applications. Design/methodology/approach NiTi alloy pellets were compacted and sintered at 900°C for 1 h in an inert argon atmosphere, followed by aging at 500°C for 1, 2 and 3 h. Microstructural characterization and electrochemical testing were conducted to assess porosity, phase formation, oxide distribution and corrosion resistance. Findings Aging treatments led to reduced porosity, with the 3h-aged sample showing 24.2% porosity compared to 25.6% in the sintered-only condition. Microstructural analysis identified the presence of Ni-rich and Ti-rich regions and phases such as Ti2Ni, NiTi and Ni3Ti. Aging also promoted uniform oxide formation, increasing with treatment duration. Electrochemical results demonstrated a significant improvement in corrosion resistance with longer aging times. Originality/value This study offers a novel approach by optimizing aging treatments to enhance the microstructure and bio-corrosion resistance of NiTi alloys fabricated through powder metallurgy. Unlike previous works, it provides a detailed correlation between aging duration, oxide formation and electrochemical performance. The findings contribute valuable insights for tailoring NiTi alloys for biomedical applications, particularly in improving corrosion resistance without compromising structural integrity.