Comparative Study of Corrosion Resistance in Aged versus Newly Fabricated Titanium Alloys

Thesis Abstract

Corrosion resistance of titanium alloys is critically important for their application in biomedical, aerospace, and chemical industries, yet the comparative effects of alloy aging processes on corrosion behavior remain insufficiently understood. This study aims to evaluate and compare the corrosion resistance of aged versus newly fabricated titanium alloys, with specific objectives to analyze surface morphology, identify electrochemical properties, and determine the influence of aging on corrosion mechanisms. The research adopts a quantitative, experimental design situated within a positivist paradigm, targeting a population of commercially available Ti-6Al-4V alloys subjected to controlled aging treatments. A total of 60 samples, evenly divided between aged and unaged categories, were prepared following standardized heat treatment protocols. Data collection involved electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests, and surface characterization via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Reliability and validity of these instruments were established through calibration, replication, and cross-validation with established standards. Data analysis was conducted primarily through Analysis of Variance (ANOVA) and regression analysis to discern statistically significant differences and relationships between aging status and corrosion parameters, complemented by thematic analysis of surface morphological features. The study hypothesizes that aging significantly alters the corrosion resistance of titanium alloys, potentially through microstructural modifications influencing passive film stability. The anticipated findings include that aged titanium alloys demonstrate enhanced corrosion resistance—evidenced by higher charge transfer resistance and lower corrosion current densities—compared to their unaged counterparts. SEM analysis is expected to reveal more uniform passive films and fewer localized corrosion attack sites on aged samples, supporting the electrochemical results. These findings are expected to fill existing gaps in the literature, particularly in elucidating the microstructural and electrochemical transformations induced by aging processes, and how these impact corrosion resistance in practical settings. The contribution to knowledge lies in providing a detailed, comparative analysis of corrosion behaviors influenced by aging, integrating electrochemical, morphological, and compositional data to offer a holistic understanding of the underlying mechanisms. This research advances theoretical frameworks such as the passivation theory and electrochemical kinetics, demonstrating their applicability in aging-treated titanium alloys. Furthermore, it offers practical insights for industries where alloy longevity and durability are paramount, informing heat treatment protocols and maintenance strategies. The main conclusion suggests that properly optimized aging treatments can significantly improve the corrosion resistance of titanium alloys, extending their service life in aggressive environments. Based on the findings, the thesis recommends adopting specific aging parameters to enhance corrosion performance and encourages further research into the long-term effects of cyclical aging and service conditions. Future studies should also explore the integration of alloying elements and surface modification techniques to further augment corrosion resistance. Overall, the research underscores the importance of heat treatment processes in alloy performance optimization and provides a scientific basis for developing more resilient titanium-based materials for critical applications.