Comparison study of Selective Laser melted Ti6Al4V and Ti6Al4V-8Ta Alloys: Mechanical & corrosion properties

Abstract

This work explores the use of Selective Laser Melting (SLM) to enhance the mechanical and corrosion properties of titanium-tantalum (Ti6Al4V-8Ta) alloys for biomedical applications. The study addresses the limitations of the widely used Ti6Al4V alloy, such as potential aluminum and vanadium toxicity, by incorporating tantalum (Ta), which offers superior biocompatibility and corrosion resistance. Comprehensive characterization is performed using Scanning Electron Microscopy (SEM) to analyze the chemical composition and particle morphology, while particle size distribution is measured using a Mastersizer. Mechanical testing reveals that the Ti6Al4V-8Ta alloy exhibits slightly reduced mechanical properties compared to Ti6Al4V, with an ultimate tensile strength (UTS) of 1216.73 ± 3.20 MPa, yield strength (YS) of 1058.67 ± 24.49 MPa, and elastic modulus of 99.64 ± 5.52 GPa. In comparison, Ti6Al4V has a UTS of 1222.69 ± 2.63 MPa, YS of 1063.87 ± 49.19 MPa, and elastic modulus of 106.38 ± 12.44 GPa. Microstructural analysis demonstrates a refined acicular martensitic structure, which improves toughness, while fractographic examination reveals both ductile and brittle fracture features, suggesting enhanced durability with the addition of Ta. Corrosion testing using potentiodynamic analysis and Electrochemical Impedance Spectroscopy (EIS) shows that Ti6Al4V-8Ta offers improved corrosion resistance. It exhibits a lower corrosion current density of 1.89 ± 0.38 μA/cm² compared to 7.23 ± 1.40 μA/cm² for Ti6Al4V, and a higher polarization resistance (Rp) of 24547.67 ± 12,157.40 Ω·cm² compared to 6762.36 ± 3796.68 Ω·cm² for Ti6Al4V. Additionally, the corrosion rate of Ti6Al4V-8Ta is 0.043 ± 0.023 mm/a, nearly half that of Ti6Al4V (0.093 ± 0.076 mm/a). Improved wettability is also observed, with Ti6Al4V-8Ta showing contact angles of 48.12 ± 4.36° (0° print angle) and 57.56 ± 3.03° (90° print angle), compared to 41.44 ± 1.18° and 47.61 ± 3.95° for Ti6Al4V. In conclusion, the Ti6Al4V-8Ta alloy developed using SLM achieves a favorable combination of mechanical performance and enhanced corrosion resistance. Although mechanical properties are slightly reduced, the significant improvements in corrosion resistance and hydrophobicity make Ti6Al4V-8Ta a promising candidate for long-term biomedical applications. This study highlights the potential of advanced manufacturing techniques to develop next-generation biomaterials that ensure safer and more durable implants.