Microstructure and Mechanical Properties of Ti-Mo-Zr-Cr Biomedical Alloys by Powder Metallurgy

[EN] Titanium and its alloys have been widely used as biometals due to their excellent biocompatibility, corrosion resistance and moderate mechanical properties. Ti-15Mo-6Zr-based alloys and a series of Ti-15Mo-6Zr-xCr (x = 1, 2, 3, 4 wt.%) alloys were designed and fabricated by powder metallurgy for the first time to develop novel biomedical materials. The microstructure, internal porosity and mechanical properties of the sintered Ti-15Mo-6Zr and Ti-15Mo-6Zr-xCr alloys were investigated using scanning electronic microscopy (SEM) and bending and compression tests. The experimental results indicated that the microstructure and mechanical properties of these alloys changed as different Cr levels were added. The addition of small Cr levels further increased the β-phase stability, improving the properties of the Ti-15Mo-6Zr-xCr alloy. However, all of the alloys had good ductility, and the Ti-15Mo-6Zr-2Cr alloy had lower bending and compression moduli (31 and 23 GPa, respectively) than the Ti-15Mo-6Zr-based alloys (40 and 36 GPa, respectively). Moreover, the Ti-15Mo-6Zr-2Cr alloys exhibited higher bending and compression strength/modulus ratios, which were as large as 48.4 and 52.2, respectively; these were higher than those of the Ti-15Mo-6Zr-based alloy (41.3 and 33.6, respectively). In the search for a better implant material, β phase Ti-15Mo-6Zr-2Cr, with its low modulus, ductile properties and reasonably high strength, is a promising candidate.The authors thank the Ministry of Economy and Competitiveness for financially supporting the research project MAT2014-53764-C3-1-R and the European Commission through the Erasmus Mundus scholarship program WELCOME. The European Commission via FEDER funds allowed for the purchase of equipment for research and Microscopy Service of the Polytechnic University of Valencia.Elshalakany, AB.; Ali, S.; Amigó Mata, A.; Eessaa, AK.; Mohan, P.; Osman, T.; Amigó, V. (2017). Microstructure and Mechanical Properties of Ti-Mo-Zr-Cr Biomedical Alloys by Powder Metallurgy. Journal of Materials Engineering and Performance. 26(3):1262-1271. doi:10.1007/s11665-017-2531-zS12621271263M. Geetha, A.K. Singh, R. Asokamani, and A.K. Gogia, Ti Based Biomaterials, the Ultimate Choice for Orthopaedic Implants—A Review, Prog. Mater Sci., 2009, 54, p 397–425M. Ahmed, D.G. Savvakin, O.M. Ivasishin, and E.V. Pereloma, The Effect of Ageing on Microstructure and Mechanical Properties of Powder Ti-5Al-5Mo-5V-1Cr-1Fe Alloy, Mater. Sci. Eng., 2014, A605, p 89–97M. Niinomi, Mechanical Biocompatibilities of Titanium Alloys for Biomedical Applications, J. Mech. Behav. Biomed. Mater., 2008, 1(30–4), p 2M.P. Licausi, A. IgualMun, and V.A. Borrás, Influence of the Fabrication Process and Fluoride Content on the Tribocorrosion Behaviour of Ti6Al4V Biomedical Alloy in Artificial Saliva, J. Mech. Behav. Biomed. Mater., 2013, 20(2013), p 137–148I. Cvijovic-Alagic, N. Gubeljak, M. Rakin, Z. Cvijovic, and K. Geric, Microstructural Morphology Effects on Fracture Resistance and Crack Tip Strain Distribution in Ti-6Al-4V Alloy for Orthopedic Implants, Mater. Des., 2014, 53, p 870–880Y.C. Chen, J.H. Chern Lin, and C.P. Ju, Effects of Post-aging Cooling Condition on Structure and Tensile Properties of Aged Ti-7.5Mo Alloy, Mater. Des., 2014, 54, p 515–519E.P. Lautenschlager and P. Monaghan, Titanium and Titanium Alloys as Dental Materials, Int. Dent. J., 1993, 43, p 245–253M. Long and H.J. Rack, Titanium Alloys in Total Joint Replacement—A Materials Science Perspective, Biomaterials, 1998, 19, p 1621–1639M. Long and H.J. Rack, Titanium Alloys in Total Joint Replacement a Materials Science Perspective, Biomaterials, 1998, 19, p 1621–1639M. Niinomi, Mechanical Properties of Biomedical Titanium Alloys, Mater. Sci. Eng., A, 1998, 243, p 231–236E. Cheal, M. Spector, and W. Hayes, Role of Loads and Prosthesis Material Properties on the Mechanics of the Proximal Femur After Total Hip Arthroplasty, J. Orthop. Res., 1992, 10, p 405–422J. Fan, M. Lu, H. Cheng, J. Tian, and B. Huang, Effect of Alloying Elements Ti, Zr on the Property and Microstructure of Molybdenum, Int. J. Refract. Met. Hard Mater., 2009, 27, p 78–82W.F. Ho, S.C. Wu, S.K. Hsu, Y.C. Li, and H.C. Hsu, Effects of Molybdenum Content on the Structure and Mechanical Properties of as-Cast Ti-10Zr-Based Alloys for Biomedical Applications, Mater. Sci. Eng., C, 2012, 32, p 517–522W.F.A. Ho, Comparison of Tensile Properties and Corrosion Behavior of Cast Ti-7.5Mo with c.p. Ti, Ti-15Mo and Ti-6Al-4V Alloys, J. Alloys Compd., 2008, 464, p 580–583Y.L. Zhou and D.M. Luo, Corrosion Behavior of Ti-Mo Alloys Cold Rolled and Heat Treated, J. Alloys Compd., 2011, 509, p 6267–6272N.T.C. Oliveira and A.C. Guastaldi, Electrochemical Stability and Corrosion Resistance of Ti-Mo Alloys for Biomedical Applications, Acta Biomater., 2009, 5, p 339–405Y. Chen, L. Xu, Z. Liu, F. Kong, and Z. Chen, Microstructures and Properties of Titanium Alloys Ti-Mo for Dental Use, Trans. Nonferrous Met. Soc. China, 2006, 16, p 824–828W.-F. Ho, S.-C. Wu, H.-W. Wanga, and H.-C. Hsu, Effects of Cr Addition on Grindability of Cast Ti-10Zr Based Alloys, Mater. Chem. Phys., 2010, 121, p 465–471M.J. Donachie, Titanium: A Technical Guide, 2nd ed., ASM International, Metals Park, 2000R.G. Craig, Restorative Dental Materials, 9th ed., CV Mosby, St. Louis, 1993H.C. Hsu, S.C. Wu, S.K. Hsu, T.F. Lin, and W.F. Ho, Structure and Mechanical Properties Of as-Cast Ti-5Nb-xCr Alloys, Mater. Des., 2013, 51, p 268–273H.-C. Hsu, S.-C. Wu, S.-K. Hsu, C.-T. Li, and W.-F. 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Sci. Eng., C, 2010, 30, p 904–90

Comportamiento frente a la oxidación de aleaciones de titanio alfa + beta

[EN] Las aleaciones alfa+beta, presentan excelentes propiedades mecánicas y frente a la corrosión lo que las hace excelentes candidatas para su aplicación en la industria química y aeronáutica, pero es importante mejorar su comportamiento frente a elevadas temperaturas, sobre todo su oxidación a esas temperaturas. En el presente trabajo se estudia la obtención de aleaciones + del tipo Ti-3%at. X (Nb, Mo, Ta) por vía pulvimetalúrgica a partir de mezcla elemental de polvos y su caracterización microestructural, con análisis específico de su resistencia a la oxidación a elevadas temperaturas. La microestructura se caracteriza mediante microscopía óptica y electrónica. La resistencia mecánica de las aleaciones se obtiene mediante ensayos de flexión y análisis fractográfico. La resistencia frente a la oxidación se ha determinado mediante una termobalanza Q50 de TA Instruments a 900º durante 200 minutos. Los mecanismos de corrosión se han analizado a través de sus óxidos superficiales, caracterizados mediante microscopía electrónica de barrido (SEM) y microscopía de fuerza atómica (AFM). Todas las aleaciones investigadas presentan estructura + con densidades entre el 90 y 94%. Además, presentan elevada resistencia a flexión, alrededor de los 1750-1800 MPa de carga de rotura, y elevada dureza; con una resistencia a la oxidación sensiblemente mayor que la correspondiente al titanio puro comercial. La difracción de rayos-X (XRD) y espectroscopia Raman confirman la formación de óxidos de titanio como fase principal. En conclusión la adición de los elementos de aleación aumenta en dos veces su resistencia frente a la oxidación a elevadas temperaturas.Los autores agradecen al MINECO la financiación del proyecto de investigación bilateral con Brasil PIB2010BZ-00448, a la UE por la financiación FEDER UPOV08-3E-005 para la compra de equipamiento y a la Generalitat Valenciana por la ayuda ACOMP/2013/094.Vicente Escuder, A.; Schalht, A.; Amigó Mata, A.; Amigó Borrás, V. (2014). Comportamiento frente a la oxidación de aleaciones de titanio alfa + beta. Revista Colombiana de Materiales (En linea). (5):177-183. http://hdl.handle.net/10251/65573S177183

Investigations of Ti Binary Alloys Manufactured by Powder Metallurgy for Biomaterial Applications

[EN] Biomaterials encompass synthetic alternatives to the native materials found in our body. They have shown rapid growth in the field of elderly population demands with the prolongation of human life. Titanium is one of the biomaterials with excellent properties and biocompatibility. However, its high stiffness may cause weakening in the structures. To sort out this problem, Ti-Cr, Ti-Mo, and Ti-Cu alloys were produced by powder metallurgy. Metal powders were mixed by mechanical alloying. After pressing and sintering, characterizations were carried out by scanning electron microscopy, X-ray diffraction, electron backscattering diffraction, and three points bending test.The authors thank the Ministerio de Economia y Competitividad of Spain for the research project MAT2014-53764-C3-1-R, An European Commission by FEDER funds for the purchase of equipment, the Generalitat Valenciana by the PROMETEO/2016/040 project.Atay, HY.; Rodríguez, M.; Amigó Mata, A.; Vicente-Escuder, Á.; Amigó, V. (2018). Investigations of Ti Binary Alloys Manufactured by Powder Metallurgy for Biomaterial Applications. Acta Physica Polonica A. 134(1):415-418. https://doi.org/10.12693/APhysPolA.134.415S415418134

Desarrollo de las aleaciones de titanio y tratamientos superficiales para incrementar la vida útil de los implantes

[EN] The population aging together with increase of life expectancy forces the development of new prosthesis which may present a higher useful life. The clinical success of implants is based on the osseointegration achievement. Therefore, metal implants must have a mechanical compatibility with the substituted bone, which is achieved through a combination of low elastic modulus, high flexural and fatigue strength. The improvement, in the short and long term, of the osseointegration depends on several factors, where the macroscopic design and dimensional, material and implant surface topography are of great importance. This article is focused on summarizing the advantages that present the titanium and its alloys to be used as biomaterials, and the development that they have suffered in recent decades to improve their biocompatibility. Consequently, the implants evolution has been recapitulated and summarized through three generations. In the recent years the interest on the surface treatments for metallic prostheses has been increased, the main objective is achieve a lasting integration between implant and bone tissue, in the shortest time possible. On this article various surface treatments currently used to modify the surface roughness or to obtain coatings are described it; it is worthy to mention the electrochemical oxidation with post-heat treated to modify the titanium oxide crystalline structure. After the literature review conducted for prepare this article, the beta titanium alloys, with a nanotubes surface of obtained by electrochemical oxidation and a subsequent step of heat treatment to obtain a crystalline structure are the future option to improve long term biocompatibility of titanium prostheses.[ES] El envejecimiento de la población junto con el incremento de la esperanza de vida, obligan al desarrollo de prótesis que presenten un periodo de vida útil cada vez mayor. El éxito clínico de los implantes está basado en la consecución de la osteointegración. Por lo tanto, las prótesis metálicas necesitan disponer de una compatibilidad mecánica con el hueso que sustituyen, que se consigue mediante una combinación de bajo módulo elástico, alta resistencia a la rotura y a fatiga. La mejora, a corto y largo plazo, de la osteointegración es función de múltiples factores, de entre los cuales son de gran importancia su diseño macroscópico y dimensional, el material y la topografía superficial del implante. Este artículo se centra en resumir las ventajas que presentan el titanio y sus aleaciones para ser empleadas como biomateriales, y la evolución que han sufrido estas, en las últimas décadas, para mejorar su biocompatibilidad. En consecuencia, se ha recapitulado la evolución que han sufrido los implantes, resumiéndose a través de tres generaciones. En los últimos años se ha incrementado el interés en los tratamientos superficiales de las prótesis metálicas, con el objetivo de alcanzar una integración del tejido óseo duradera y en el menor tiempo posible. En este artículo se exponen varios tratamientos superficiales utilizados actualmente para modificar la rugosidad o para obtener recubrimientos superficiales; cabe destacar la oxidación electroquímica con tratamiento térmico, para modificar la estructura cristalina de los óxidos de titanio. Tras la revisión bibliográfica llevada a cabo para la redacción de este artículo, las aleaciones β de titanio, con una superficie de nanotubos obtenida mediante oxidación electroquímica y una etapa posterior de tratamiento térmico para obtener una estructura cristalina, son la opción de futuro para mejorar la biocompatibilidad a largo plazo de las prótesis de titanio.Los autores desean agradecer al Ministerio de Economía y competitividad el apoyo financiero a través del proyecto de investigación MAT2014-53764-C3-1-R y a la Generalitat Valenciana a través del apoyo PROMETEO/2016/040. A la Comisión Europea a través de los fondos FEDER que han permitido la adquisición de los equipos para la investigación y del Servicio de Microscopía de la Universitat Politècnica de València.Lario-Femenía, J.; Amigó Mata, A.; Vicente-Escuder, Á.; Segovia-López, F.; Amigó, V. (2016). Desarrollo de las aleaciones de titanio y tratamientos superficiales para incrementar la vida útil de los implantes. 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Effect of Fe Addition on Microstructure and Properties of Powder Metallurgy Ti35Nb10Ta Alloy

[EN] The high contents of noble refractory elements of Ti35Nb10Ta (wt.%) alloy difficult the diffusion of them. The stabilization of the ß phase can be favored by the addition of Fe in ß-Ti alloys. In this work, elemental powders mixture with different contents of Fe (0, 1.5, 3.0 and 4.5 wt.%) were used. These powders were compacted with uniaxial pressure of 600MPa and sintered at 1250°C in high vacuum. The porosity obtained after sintering shows a dependence on the particle size of iron used, and homogeneous pores distribution was observed. The analyzed microstructure mainly corresponds to ß-Ti phase, with small fractions of ¿ phase appearing at grain boundaries, which decreases with increasing of Fe content. The microstructure showed good compositional homogeneity of Fe and Ta and some lack of diffusion related to large amount of undissolved Nb particles. Addition of Fe lead to a decrease in bending strength of Ti35Nb10Ta alloy.Authors would like to thank the Universitat Politècnica de València (UPV) for the financial support by Researcher Training Program. The Spanish Ministry of Economy and Competitiveness under the Research Project MAT2014-53764-C3-1-R and Generalitat Valenciana for the financial support. European Commission due to FEDER founds to acquire investigation equipment and the Electron Microscopy Service (SME) of the Universitat Politècnica de València (UPV).Amigó Mata, A.; Afonso, C.; Amigó, V. (2017). Effect of Fe Addition on Microstructure and Properties of Powder Metallurgy Ti35Nb10Ta Alloy. Materials Science Forum. 899:206-211. doi:10.4028/www.scientific.net/MSF.899.206S20621189

Effects of Fe and Mo Content on the Microstructure and Mechanical Properties of Ti-Mo based alloys prepared by Elemental blend and Mechanical alloying technique

[EN] Ti and its alloys are mostly used as biomaterials due to its unique properties like high corrosion resistance, low elastic modulus, high mechanical strength/ density ratio, good biocompatibility etc. Ti-β alloys based on the Ti-Mo alloy system shows much more interest for biomaterials. Addition of Zr and small amount of Fe improves the β-phase stability and improving the properties of Ti-Mo alloy. These alloys can be produced by powder metallurgy (PM) using Elemental Blend (EB) technique (600 MPa compaction pressure) and Mechanical Alloying (MA) technique with (600 and 900 MPa compaction pressure). This paper describes the microstructural characterization obtained by SEM and mechanical properties obtained by bending test, Archimedes test and ultrasonic test of Ti-Mo-Zr-Fe alloys made by elemental blend and Mechanical Alloying. Mechanical properties and Microstructure of these powder mixing processes also compared. The addition of small amounts of Fe further increases β-phase stability, improving the properties of Ti¿15Mo¿6Zr¿xFe alloy. In the search for a better implant material, Ti¿12Mo¿6Zr¿2Fe, with its low modulus, ductile property, and reasonably high strength, is a promising candidate.The authors wish to thank the Ministry of Economy and competitiveness through the financial support of the research project MAT2014-53764-C3-1–R, The European commission the Erasmus mundus scholarship program Namaste and the Generalitat Valenciana through support ACOMP/2014/151.The European Commission via FEDER funds that have allowed the purchase of equipment for research and Microscopy Service of the Polytechnic University of Valencia.Mohan, P.; Amigó Mata, A.; Amigó, V. (2016). Effects of Fe and Mo Content on the Microstructure and Mechanical Properties of Ti-Mo based alloys prepared by Elemental blend and Mechanical alloying technique. Transactions of Powder Metallurgy Association of India. 42(1):25-31. http://hdl.handle.net/10251/103622S253142

Surface Modification of Ti-35Nb-10Ta-1.5Fe by the Double Acid-Etching Process

[EN] Surface topography and composition influence the osteoblastic proliferation and osseointegration rates, which favor the biomechanical stability of bone anchoring and implants. In recent years, beta titanium alloys have been developed, and are composed of biocompatible elements, have low elastic modulus, high corrosion resistance, and mechanical properties to improve the long performance behavior of biomaterials. In the present research, the influence of the acid-etching process was studied in Ti6Al4V ELI and Ti35Nb10Ta1.5Fe. Samples were etched in a two-step acid treatment. Surface roughness parameters were quantified under a confocal microscope, topography was studied by scanning electron microscopy, and surface composition was analyzed with energy dispersive X-ray spectroscopy. The results revealed that the two-step acid treatment changes the topography of the ß alloy, increases the surface area, and changes the chemical composition of the surface. Two differentiated regions were identified in the Ti35Nb10Ta1.5Fe alloy after the acid-etching process: The ¿ + ß region with higher values of mean roughness due to the lower chemical resistance of this region; and the ß region with lower values of roughness parameters.The authors wish to thank the Spanish Ministry of Economy and Competitiveness for the financial support of Research Project MAT2014-53764-C3-1-R, the Generalitat Valenciana for support through PROMETEO 2016/040, the European Commission via FEDER funds that have allowed the purchase of equipment for research purposes and for the Microscopy Service at the Polytechnic University of Valencia.Lario, J.; Amigó Mata, A.; Segovia-López, F.; Amigó, V. (2018). Surface Modification of Ti-35Nb-10Ta-1.5Fe by the Double Acid-Etching Process. Materials. 11(4):1-11. https://doi.org/10.3390/ma11040494S11111

Effect of Bactericidal Elements Addition on the Microstructure and Mechanical Properties of Ti34Nb Alloy

[EN] The functionalization of ß-Ti alloys by the addition of small amounts of bactericidal elements is interesting for biomedical applications. Thus, alloying pure titanium with highly biocompatible elements such as Nb or Ta, stabilizes the ß phase of the resulting alloy although they can also include difficulties during the fabrication process due to their refractory nature. This work studies the effect of small additions of Ag and Cu (1.5 to 3 wt.%) on the microstructure and mechanical properties of the Ti34Nb (wt.%) alloy processed by powder metallurgy. The blend elemental powders were mixed (30 rpm during 30 min). The samples were compacted at 600 MPa and sintered at 1250 ºC during 3 hours. The microstructure was analyzed by X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscope with X-Ray Spectroscopy (FESEM/ EDS). The mechanical properties were obtained by bending tests; the elastic modulus was measured by ultrasonic methods and the porosity by Archimedes test. Cu addition generates the appearance of ¿ phase sheets inside the ß phase grains. Cu also decreases the open porosity and increases the closed porosity of the material. On the contrary, Ag addition does not influence the stabilization of the ß phase and it does not modify the density, thus the total porosity of the resulting material. With respect to the influence of the alloying elements on the elastic modulus (E) of the alloys, the E of the Ti34Nb (76.8 GPa) increases with the Cu addition (92.6 GPa) and decreases with the Ag one (68.9 GPa). Therefore, silver addition, which does not modify the microstructure and slightly decrease the mechanical properties of the Ti34Nb, can be considered a good alloying element to provide antibacterial features to the titanium alloy without losing performance.The authors would like to thank the Ministry of Economy and Competitiveness for the financial under the Research Project MAT2014-53764-C3-1-R and MAT2014-53764-C3-3-R. Universitat Politècnica de València for the financial support by Researcher Training Program with the predoctoral contract dated in 28 february of 2014, European Comision due to FEDER founds to acquire investigation equipment and the Electron Microscopy Service of the Universitat Politècnica de Valencia.Gil, E.; Amigó Mata, A.; Igual Muñoz, AN.; Amigó, V. (2017). Effect of Bactericidal Elements Addition on the Microstructure and Mechanical Properties of Ti34Nb Alloy. Materials Science Forum. 899:185-190. doi:10.4028/www.scientific.net/MSF.899.185S18519089