Nanotube formation and morphology change of Ti alloys containing Hf for dental materials use

In this paper, Ti-Hf (10, 20,30 and 40 wt%) alloys were prepared by arc melting, and subjected to heat treatment for 24 h at 1000 degrees C in an argon atmosphere. Formation of surface nanotubes was achieved by anodizing a Ti-Hf alloy in 1.0 M H3PO4 electrolytes with small amounts of NaF at room temperature. Microstructures of the alloys and nanotube morphology were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The homogenized Ti-Hf alloys had a needle-like microstructure of alpha phase, and nanotubes formed on Ti-xHf alloys had the anatase phase after treatment that promoted crystallization. Uniform nanotubes formed for Hf contents up to 20 wt%. Irregular nanotubes formed on the Ti-30Hf and Ti-40Hf alloys. The structure of the irregular layers on the Ti-30Hf and Ti-40Hf alloys had nanotubes of two sizes. Increasing the Hf content in Ti led to the formation of nanotubes with more narrow size. The pores in the nanotubes typically had a diameter ranging from 80-120 nm and a length of approximately 1.7 mu m. It is concluded that nanotube morphology on Ti-Hf alloys can controlled by varying the amount of Hf. (C) 2009 Elsevier B.V. All rights reserved.