Morphology and nanomechanical properties of the ultrafine-grained Ti-13Nb-13Zr alloy surface obtained using electrochemical anodization

Abstract

Lower value of modulus of elasticity, closer to that of a bone, is one of the crucial surface properties in accepting the implant material from the surrounding tissue, and reduces the possibility of slow disappearance of bone in contact with the implant. In the present study, ultrafine-grained (UFG) Ti-13Nb-13Zr alloy was obtained using high pressure torsion process (HPT) under a pressure of 4.1 GPa with a rotational speed of 0.2 rpm up to 5 rotations at room temperature. Nanostructured surface on coarse-grained (CG) and UFG Ti-13Nb-13Zr alloy was formed using electrochemical anodization in the 1M H3PO4 + NaF electrolyte, during 60 and 90 minutes. Scanning electron microscopy (SEM) was used to characterise the morphology of the surface, while nanomechanical properties of the surface, modulus of elasticity and nanohardness were determined using the nanoindentation test. Also, in order to characterise deformation of the nanotubes after nanoindentation test, SEM was done. It was shown that the nanotubular oxide layer was formed as result of the electrochemical anodization process during both anodizing times. The surface of anodized alloys has lower modulus of elasticity than surface of non-anodized ones. Anodized UFG alloy had the lowest modulus of elasticity of the surface when compared to other tested samples, which makes it more acceptable for biomedical usage.