A Study on Ti-Nb Alloys with Different Composition for Orthopedic Application Using MD Simulations and Experiments

The nanoindentation behavior of Ti-Nb alloy with varying compositions (5–25 wt.% of Nb in Ti) is investigated using molecular dynamics simulations. Single crystals of different Ti-Nb alloys are generated to perform nanoindentation simulation using a spherical indenter. A modified embedded atom method potential is used for the simulation. Young's modulus and hardness values are estimated for different alloy compositions, and the alloy with a minimum value of Young's modulus has been designed for orthopedic application. The Ti-20 wt.% Nb alloy with Young's modulus and hardness values of 55.8 ± 2.67 GPa and 2.34 ± 0.05 GPa, respectively, demonstrates a Young's modulus value closer to that of human bones, and so has the potential to minimize the stress shielding effect in orthopedic applications. With the help of the dislocation extraction algorithm (DXA) the dislocation density at different stages of the nanoindentation process is analyzed to understand the mechanical behavior of the alloy during the nanoindentation. Ti-12 wt.% Nb alloy has been fabricated by vacuum arc remelting process to validate the model. The wear mechanism of the alloy has been examined for load-bearing orthopedic applications. The Ti-Nb alloys demonstrate superior performance compared to the Ti-6Al-4V alloy and Co-Cr based alloy for orthopedic applications.