Assessment of anodization conditions and annealing temperature on the microstructure, elastic modulus, and wettability of beta-Ti40Nb alloy

In this work, it was mapped combinations of anodization conditions, annealing temperatures, and elastic modulus together with better wettability properties of low elastic modulus Ti40Nb alloy. The anodization was realized in an organic electrolyte for one hour. Thus (Ti,Nb)O-2 nanostructures grew on the surface. For the sake of optimizing the wettability, the anodization voltage was varied to obtain different nanostructured morphologies, which grew either in the form of nanotubes or nanopores. Posterior heat treatment at different temperatures (450 degrees C, 550 degrees C, and 800 degrees C) led to distinct titania crystalline phases (anatase, anatase+rutile, rutile) and different Young's moduli. Different morphologies and crystalline phases affect surface wettability properties. Although all the studied conditions showed a hydrophilic behavior (contact angle below 90 degrees), the optimized condition was found to be the samples coated with anodized nanotubes, whose annealing temperature led to a mix of anatase and rutile phases. Such morphology and phases reduced the contact angle to a minimum. The annealing temperature led the alloy elastic modulus to the lowest value (65 GPa). The optimized condition may be considered the more suitable combination for future biomedical applications. (AU)