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

Abstract 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 °C for 24 h, and then both alloys were hot rolled at approximately 1000 °C. The alloy specimens were oxidized at temperatures between 400 to 750 °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 °C for Ti–6Al–4 V alloy and above 700 °C for Ti–10Ta–10Nb alloy respectively. According to XRD results, both oxide layers were composed of mostly TiO 2 (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.