Enhanced corrosion resistance, wear behavior, and biocompatibility of Ti-6Al-4V alloy for bone implants

Ti-6Al-4V alloy is extensively utilized in biomedical applications such as bone implants due to its high corrosion resistance, favorable mechanical features, and biocompatibility. In this study, a short-time duplex aging treatment at different aging temperatures of 350, 450, 500, 550, 600, and 700 o C was conducted on solution-treated alloys. The microstructural observations revealed a bimodal structure consisting of globular α and α/β lamellae. By increasing the aging temperature, the globular α phase and lamellae experienced growth. With an increase in aging temperature, the strength values decreased while elongation increased. Also, the hardness of aged alloys increased after aging. The hardness grew as the aging temperature decreased. Similarly, the wear resistance improved as the aging temperature decreased. Additionally, the main wear mechanisms were abrasive wear, adhesive wear, and delamination. The aged alloys were less worn at lower aging temperatures, especially after the second stage of aging. Based on the result of in-vitro corrosion, the aged samples showed better corrosion resistance compared to the solution-treated one. In addition, the surfaces were less corroded after the second stage of aging compared to the first stage of aging. Also, an increase in aging temperature resulted in a greater thickness of the oxide layer and enhanced corrosion resistance. Furthermore, a better cytotoxic response of alloys was obtained after employing aging treatment. As the surface roughness and the thickness of the oxide layer increased, improved interaction between chondrocytes and alloys was observed, demonstrating its excellent potential as bone implants.