Materials Science and Engineering A 432 (2006) 108–112 Microstructural and mechanical characterization of biomedical Ti–Nb–Zr(–Ta) alloys L.M. Elias a , S.G. Schneider a,∗ , S. Schneider a , H.M. Silva b , F. Malvisi a a Faculdade de Engenharia Qu´ ımica-FAENQUIL/DEMAR, Polo Urbo Industrial, Gleba AI-6, Mondesir, C.P.116, 12600-970 Lorena, SP, Brazil b Instituto Tecnol´ ogico de Aeron´ autica-ITA, P¸ ca. Marechal do Ar Eduardo Gomes, 50, Vila das Ac´ acias, S ˜ ao Jos´ e dos Campos-SP 12228-904, Brazil Received 20 April 2005; received in revised form 19 May 2006; accepted 31 May 2006 Abstract In recent years there has been a significant development of novel implant alloys based on -Ti such as Ti–Nb–Zr and Ti–Nb–Zr–Ta alloys systems. The purpose of this work is to provide characterization of Ti–35.3Nb–5.1Ta–7.1Zr and Ti–41.1Nb–7.1Zr alloys, in which Nb will substitute the atomic amount of Ta, with emphasis in the property-microstructure-composition relationships. These alloys are produced from commercially pure materials (Ti, Nb, Zr and Ta) by an arc melting method. All ingots were submitted to sequences of heat treatment (1000 ◦ C/2 h - WQ), cold working by swaging procedures and other heat treatment (1000 ◦ C/2 h - WQ). Specimens, in as cast and heat-treated condition, were examined by light and scanning electron microscopy (SEM). These results suggested the presence of - and -phases. Mechanical properties were based on tensile and hardness tests. These alloys exhibit a lower modulus than that of conventional Ti alloys and the other mechanical properties are suitable for biomedical applications. © 2006 Elsevier B.V. All rights reserved. Keywords: Biomaterial; Ti–Nb–Zr(–Ta) alloys; Mechanical properties 1. Introduction Selecting materials for different components in biomedical devices depends especially on several factors. First, the implant materials must possess an excellent biocompatibility. Moreover, it must have an excellent corrosion resistance and appropriate mechanical properties. Low elastic modulus is required to be close to that of a human bone, in order to transfer the adequate mechanical stress to the surrounding bone [1]. Metallic biomaterials such as stainless steels, Co-based alloys, titanium and titanium alloys have been extensively used in the medical applications [2]. However, they can cause some health problems because of the release of toxic metal ions, and they can also lead to resorption of adjacent bone tissues due to great difference in modulus between the implant device and adjacent bone tissues [3]. Titanium and titanium alloys are well-suited as clinically used biomaterials because their biological, mechanical and physical properties play significant roles in the longetivity of ∗ Corresponding author. Tel.: +55 12 3159 9929; fax: +55 12 3153 3006. E-mail address: sandra@demar.faenquil.br (S.G. Schneider). the prostheses and implants [1]. The Ti–6Al–4V alloy had been developed for aerospatial and naval industries; it was one of the first titanium biomaterial introduced in implantable components and devices. Nevertheless, due to toxicity effects caused by Al and V and high elastic modulus, new alloys that present lower elastic modulus and do not contain these ele- ments are receiving a great deal of attention [3–5]. Recent biomaterials research has been focused on -titanium alloys because processing variables can be controlled to lead selected results. Tissue reaction studies have identified Ti, Nb, Zr and Ta as non-toxic elements as they do not cause any adverse reaction in human body. In addition, Nb and, to a lesser extent, Ta, both act as -stabilizers, to form homogeneous solid solutions, while Zr acts as a neutral element for forming a homogeneous solid solution in the - and -phases. Furthermore, Nb and Ta are found to reduce the elastic modulus when alloyed with titanium in certain preferred quantities [3,6,7]. Studies about Ti–Nb–Ta–(Zr) system have shown that phase transformations are sensitive to both cooling rate and chemical composition. Fig. 1 illustrates a schematic continuous cooling transformation (CCT) diagrams for the Ti–Nb–Ta–Zr alloys con- taining approximately 7 wt.% Zr [8]. 0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.06.013