Surface characterization and mechanical property evaluation of thermally oxidized Ti-6Al-4V Amit Biswas, Jyotsna Dutta Majumdar ⁎ Department of Metal. & Maters. Engg., I. I. T. Kharagpur, W. B. – 721302, India ARTICLE DATA ABSTRACT Article history: Received 26 November 2007 Received in revised form 30 August 2008 Accepted 9 December 2008 The present study concerns development of a thin and adherent oxide film on the surface of Ti-6Al-4V by thermal oxidation. Thermal oxidation was carried out over a range of temperature between 400 to 600 °C and a time from 25 h to 60 h. A detailed characterization of the surface and cross section of the oxidized surface was carried out by optical/scanning electron microscopy and X-ray diffraction techniques. Finally, the mechanical properties of the oxidized surface in terms of microindentation hardness and wear resistance were evaluated as a function of oxidation parameters. Surface oxidation of Ti-6Al-4V at 600 °C for 36 h offered a defect free oxide scale with improved hardness and wear resistance. © 2008 Published by Elsevier Inc. Keywords: Ti-6Al-4V Thermal oxidation Microstructure Microhardness Wear 1. Introduction Titanium and its alloys are widely used as surgical implants because of their good corrosion resistance, high specific strength and biocompatibility [1–3]. However, a poor wear resistance of Ti- based alloys results in limitations for prolonged use of the component especially as an implant for hip joint and dental applications. These environments reduce the life of the compo- nent. Furthermore, loss of adhesion at the interface was found to be caused by the existence of a layer of porous titanium oxide [4]. Many methods have been used to produce the oxide layer on a Ti surface, including anodizing [5,6], oxygen diffusion [7], ion implantation [8,9], thermal oxidation [10,11] and palla- dium treated thermal oxidation [12]. However, it was observed that thermal oxidation of Ti surface shows better properties than others, because it produces a thick, highly crystalline rutile oxide film [12]. Anodizing generates anatase and/or hydrated oxides of low crystallinity [13]. Siva Rama Krishna et al. [14] studied the influence of thermal oxidation on wear resistance of titanium. They reported the formation of a thick and well adherent rutile scale on titanium, with improved wear resistance and reduced friction coefficient by thermal oxidation at 850 °C followed by furnace cooling. However the oxide layer pro- duced by prolonged thermal oxidation at high temperatures (above 800 °C) leads to oxide de-bonding [15]. On the other hand, an oxide layer produced at low temperatures and for short duration is not thick enough for potential tribological applications. Thus, an optimum choice of oxidation para- meters is important so as to produce a well adherent surface scale with optimum thickness. In the present study, an attempt has been made to develop a uniform oxide layer on the surface of Ti-6Al-4V by thermal oxidation between 400 to 600 °C. A detailed characterization of the surface and cross sectional plane of the oxidized surface has been characterized by light optical microscopy, scanning electron microscopy and X-ray diffraction techniques. Finally, the hardness and wear resistance of the oxide surface were evaluated to study the effect of thermal oxidation on the mechanical properties of the oxidized surface. MATERIALS CHARACTERIZATION 60 (2009) 513 – 518 ⁎ Corresponding author. Tel.: +91 3222 283288; fax: +91 3222 282280. E-mail address: jyotsna@metal.iitkgp.ernet.in (J. Dutta Majumdar). 1044-5803/$ – see front matter © 2008 Published by Elsevier Inc. doi:10.1016/j.matchar.2008.12.014