Titanium alloys are among the most important and frequently used class of biomaterials. In addition to biocompatibility, it is important that an implant material present satisfactory mechanical properties that allow long term use in the body. To improve such properties, different heat treatments are used, as well as doping with oxygen. The presence of interstitial oxygen in the crystal lattice causes deformation, increases the hardness, and causes modifications in anelasticity, thereby decreasing the elastic modulus. In this study, an alloy was prepared by arc melting precursor metals, heat and mechanically treated, and doped with oxygen, resulting in samples with different processing conditions. In each condition, the alloy was characterised in terms of amount of oxygen, X-ray diffraction, and optical microscopy. In addition, properties of the alloy, such as hardness and elastic modulus, were analysed.

Titanium alloys have great potential for use as biomaterials due to good biocompatibility and mechanical properties. The nickel addition to titanium improves the wear, corrosion and mechanical resistance of this element. The objective of this paper was to investigate the effects of oxygen on the structure, microstructure and some selected mechanical properties of this alloy system. The results showed that the samples present the adequate nickel concentration and low concentration of other metals. The alloys exhibit predominantly the α and intermetallic Ti2Ni phases, and the amount of it increases according to the nickel concentration. In the Ti-15Ni and Ti-20Ni alloys, this intermetallic reacted with oxygen forming Ti4Ni2O trioxide. The microstructures varied according to the processing, as well as the microhardness values. Elastic modulus values are slightly above titanium due to the formation of a new intermetallic phase but have not varied significantly with processing and doping with oxygen.

Titanium nickel (Ti-Ni) alloys with low nickel (Ni) content can be used as biomaterials because they improve the mechanical properties, corrosion, and wear resistance of commercially pure titanium (Cp-Ti). Among the mechanical properties of a biomaterial, elastic modulus and microhardness are very important, and each varies according to the microstructure and interstitial elements such as oxygen and nitrogen as well as the amount of substitutional element and thermomechanical processing. Heat treatments are used to obtain a homogeneous microstructure, free of internal stresses structural, microstructural, also to retain or change the size of the phases. In this chapter, the preparation, chemical, structural, and microstructural, and mechanical characterization of Ti-Ni alloys are presented. The structural and microstructural characterization showed the predominant presence of α and Ti 2 Ni phases. There is no clear variation of the microhardness due to the amount of nickel. The dynamic elastic modulus was slightly above the Cp-Ti due to the addition of a new intermetallic phase (Ti 2 Ni) but did not vary significantly with the amount of Ni.

RESUMOLigas de titânio representam uma importante classe de biomateriais. Além da questão da biocompatibilidade, é muito importante considerar as propriedades mecânicas de um biomaterial, que são diretamente relacionadas com a microestrutura e quantidade de elementos intersticiais presentes. No presente trabalho, a liga Ti-10%pNi foi produzida a partir da fusão dos metais titânio e níquel comercialmente puros, num forno de arco sob uma atmosfera de argônio. Em seguida, foi realizado um tratamento térmico e a amostra foi laminada. Para comprovar a composição da liga, foi realizada análise química quantitativa. A estrutura e microestrutura da liga produzida foram analisadas por difração de raios-x, microscopia óptica e microscopia eletrônica de varredura. Os resultados mostram que a liga apresenta predominantemente a fase alfa do titânio (estrutura hexagonal compacta), com precipitados lamelares proeutetóide numa matriz eutetóide composta de fase alfa e do intermetálico Ti2Ni. Palavras-chave: Liga de titânio, microestrutura, propriedades mecânicas, processamento. ABSTRACTTitanium alloys are an important class of biomaterials. Apart from the issue of biocompatibility, is very important to consider the mechanical properties of a biomaterial, which are directly related to the microstructure and interstitial elements quantity present. In the present paper, Ti-10wt%Ni was produced from the melting of commercially pure titanium and nickel in arc furnace under argon atmosphere. Then a heat treatment was carried out and the sample was hot-rolled. To prove the alloy composition, quantitative chemical analysis was performed. The structure and microstructure of the produced alloy were analyzed by x-ray diffraction, optical and scanning electron microscopy. The results show that the alloy presents predominantly titanium alpha phase (hexagonal compact structure), with proeutectoid lamellar precipitates in eutectoid matrix of alpha phase and intermetallic Ti2Ni. Keywords: Titanium alloy, microstructure, mechanical properties, processing. INTRODUÇÃOA pesquisa sobre novos biomateriais é de fundamental importância, pois com o aumento e envelhecimento da população mundial, a demanda tem aumentado substancialmente [1]. Neste sentido, o titânio e suas ligas têm sido muito utilizados como materiais biomédicos, em função da alta resistência à corrosão, ótima relação resistência mecânica/densidade e excelente biocompatibilidade [2,3] Ligas de titânio usadas tradicionalmente em próteses, como Ti-6Al-4V, apresentam falhas como liberação de íons tóxicos e propriedades mecânicas não muito satisfatórias como módulo elástico alto (cerca de 112 GPa) em comparação com o do osso (cerca de 30 GPa) devido à sua microestrutura do tipo α + β [4,5]. No caso de implantes ortopóedicos, ligas com microestrutura β são mais apropriadas devido ao menor módulo elástico, cerca de 60-80 GPa [2].No entanto, ligas de titânio com fase α, apesar de apresentarem maior módulo elástico, apresentam melhor oxidação, resistência à corrosão e soldabilidade, comparado co...