Oxidation behavior and corrosion resistance of Ti-10Ta-10Nb alloy

We have examined and discovered that a more passive oxide film by oxidation treatment can be formed on the newly designed Ti-10Ta-10Nb alloy, which is closely related to corrosion resistance and biocompatibility. Ti-6Al-4 V and Ti-10Ta-10Nb alloys were prepared by consumable vacuum arc melting and homogenized at 1050 degrees C for 24 h, and then both alloys were hot rolled at approximately 1000 degrees C. The alloy specimens were oxidized at temperatures between 400 to 750 degrees C for 30 min. The oxide films on the Ti alloys Were analyzed by optical microscope, SEM/EDX, XRD, XPS and TGA. The Corrosion resistances of the Ti alloys were evaluated by performing potentiodynamic polarization test in 0.9% NaCl and immersion test in 0.9% NaCl, 5% HCl and 1% lactic acid. Cytotoxicity test was performed in MTT assay treated L929 fibroblast cell culture by indirect method. We discovered that the oxide film on Ti-10Ta-10Nb alloy was denser and thinner compared to the oxide film on Ti-6Al-4 V alloy. The rapid increase in mass during oxidation was observed at temperatures above 650 degrees C for Ti-6Al-4 V alloy and above 700 degrees C for Ti-10Ta-10Nb alloy respectively. According to XRD results, both oxide layers were composed of mostly TiO2 (rutile) phase. The corrosion resistance of Ti-10Ta-10Nb alloy was improved by oxidation treatment. Furthermore, cytotoxicity test results indicated that moderate oxidation treatment lowers cell toxicity with the Ti-10Ta-10Nb alloy showing a more promising result compared to Ti-6Al-4 V alloy. (c) 2008 Elsevier B.V. All rights reserved.