Effect of Heat Treatment on Mechanical Properties and Corrosion Resistance of β Ti-18Mo-xCr (x = 3 & 7 wt.%) Alloy

Abstract

β-Titanium alloys have gained significant attention for orthopaedic implants due to their superior mechanical properties, including high strength and a notably lower elastic modulus compared to conventional Ti-6Al-4V alloys. In this study, Ti-18Mo-xCr (x = 3 and 7 wt.%) alloys were developed to explore novel materials for biomedical applications. The alloys were produced using Vacuum Arc Remelting (VAR) followed by solution treatment and aging heat treatments. The elastic modulus was assessed using the Sonelastic tool, while corrosion resistance was evaluated via electrochemical polarization in a 0.9% NaCl solution. Surface morphology post-corrosion was analysed using SEM-EDS. The solution-treated alloys exhibited a significantly lower elastic modulus than those subjected to aging. Furthermore, the corrosion resistance of the aging-treated alloys was markedly inferior to both the solution-treated samples and the Ti-6Al-4V alloy, primarily due to β-phase stabilization during solution treatment. Prolonged aging further compromised corrosion resistance. Among all tested conditions, the Ti-18Mo-3Cr alloy aged at 500 °C demonstrated the lowest corrosion rate of 7.7373 × 10^-5 mm/year. These findings highlight the potential of Ti-18Mo-xCr alloys as candidates for next-generation orthopaedic implants, balancing mechanical properties and corrosion resistance.