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Wednesday, December 5, 2007 - 3:00 PM
30.1

Study of New Multifunctional Ni-fee Ti Alloys for Biomedical Applications

M. Arciniegas, J. M. Manero, J. Gil Mur, Technical University of Catalonia, Barcelona, Spain; J. Peña, Elisava Escola Superior de Disseny, Barcelona, Spain; M. González, Universitat Politècnica de Catalunya, Barcelona, Spain

The main purpose of this work is produce and characterize new Ni-free Ti alloys, which present shape memory effect and low elastic modulus for using in the biomedical applications field. For that, theoretical parameters were calculated by applying density functional theory to a very simple model of the interaction between titanium and several alloying elements in order to obtain some parameters that can serve as a guide for designing these alloys. In order to test the utility of such parameters, an alloy data base with one hundred and thirty two alloys was created, which constitutes a review of shape memory and/or low elastic modulus of Ti alloys from 1970 up to 2006. The mapping of these alloys with respect to the calculated parameters permitted to identify two zones that group the alloys with either property. From this information the Ti-8.8Zr-19.1Nb and Ti-15.8Ta-19Nb alloys were designed. Samples of both alloys were thermal treated and extensively characterized.

The results showed β-phase microstructure in both alloys, with elastic moduli of 62 and 74 GPa for Ti-8.8Zr-19.1Nb and Ti-15.8Ta-19Nb alloys, respectively. This latter presented an Ms temperature of 45ºC and disperse orthorhombic α" plates with an elastic modulus of 42 GPa detected by nanoindentation tests. Biological tests confirmed the no-citotoxicity of the studied alloys together with a high proliferation of osteoblasts MG63 on their surface. Also, the adhesion tests showed results similar to those obtained on surface of Ti pure in the same studied conditions.


Summary: The main purpose of this work is produce and characterize new Ni-free Ti alloys, which present shape memory effect and low elastic modulus for using in the biomedical applications field. For that, theoretical parameters were calculated by applying density functional theory to a very simple model of the interaction between titanium and several alloying elements in order to obtain some parameters that can serve as a guide for designing these alloys. In order to test the utility of such parameters, an alloy data base with one hundred and thirty two alloys was created, which constitutes a review of shape memory and/or low elastic modulus of Ti alloys from 1970 up to 2006. The mapping of these alloys with respect to the calculated parameters permitted to identify two zones that group the alloys with either property. From this information the Ti-8.8Zr-19.1Nb and Ti-15.8Ta-19Nb alloys were designed. Samples of both alloys were thermal treated and extensively characterized. The results showed ¥â-phase microstructure in both alloys, with elastic moduli of 62 and 74 GPa for Ti-8.8Zr-19.1Nb and Ti-15.8Ta-19Nb alloys, respectively. This latter presented an Ms temperature of 45¨¬C and disperse orthorhombic ¥á¡± plates with an elastic modulus of 42 GPa detected by nanoindentation tests. Biological tests confirmed the no-citotoxicity of the studied alloys together with a high proliferation of osteoblasts MG63 on their surface. Also, the adhesion tests showed results similar to those obtained on surface of Ti pure in the same studied conditions.