Comparative study of the oxide scale thermally grown on titanium alloys by ion beam analysis techniques and scanning ele
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. Pászti KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, Hungary; and Centro de Microanálisis de Materiales, Cantoblanco, E-28049 Madrid, Spain
A. Climent-Font Departamento de Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain; and Centro de Microanálisis de Materiales, Cantoblanco, E-28049 Madrid, Spain
J.A. Jiménez Centro Nacional de Investigaciones Metalúrgicas, CSIC, E-28040 Madrid, Spain
M.F. López Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain (Received 28 September 2007; accepted 12 May 2008)
In the present work, the oxide layers developed at elevated temperature on three vanadium-free titanium alloys, of interest as implant biomaterials, were studied by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and scanning electron microscopy. The chemical composition of the alloys investigated, in wt%, was Ti–7Nb–6Al, Ti–13Nb–13Zr, and Ti–15Zr–4Nb. Upon oxidation in air at 750 °C, an oxide scale forms, with a chemical composition, morphology, and thickness that depend on the alloy composition and the oxidation time. After equal exposure time, the Ti–7Nb–6Al alloy exhibited the thinnest oxide layer due to the formation of an Al2O3-rich layer. The oxide scale of the two TiNbZr alloys is mainly composed of Ti oxides, with small amounts of Nb and Zr dissolved. For both TiNbZr alloys, the role of the Nb-content on the mechanism of the oxide formation is discussed.
I. INTRODUCTION
Titanium and titanium alloys have been widely used in medical applications due to their excellent corrosion resistance and mechanical properties. Among all commercially available alloys, Ti–6Al–4V has been the mostused titanium alloy for artificial hip joints for many years. Despite the exceptional properties of this alloy, recent investigations report on the release of metallic ions from surgical implants, which could induce harmful effects.1–5 The results of different studies indicate that metallic vanadium is strongly toxic to cells, and aluminium has been associated with potential neurological disorders.6–8 Thus, much research effort is being devoted to develop vanadium-free alloys with improved biocompat-
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2008.0281 J. Mater. Res., Vol. 23, No. 8, Aug 2008
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ibility and similar corrosion resistance and mechanical properties to Ti–6Al–4V alloy.9–15 The biocompatibility of metallic biomaterials is related to their corrosion resistance in biological systems. The excellent corrosion behavior of titanium-based alloys in aggressive environments is achieved due to the formation of a stable, tightly adherent, passive layer.16–19 This layer is nothing but the surface oxide film generated spontaneously by reaction with oxygen from the atmosphere. A possible approach to improving the corrosion resistance of titanium alloys would be to increase the thickness of the outer oxide lay
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