Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy

[EN] beta alloys based on the Ti Nb alloy system are of growing interest to the biomaterial community. The addition of small amounts of Fe and Cr further increases beta-phase stability, improving the properties of Ti Nb alloy. However, PM materials sintered from elemental powders are inhomogeneous due to restricted solid state diffusion and mechanical alloying provides a route to enhance mixing and lemental diffusion. The microstructural characteristics and bend strength of Ti Nb (Fe Cr) alloys obtained from elemental powder mixture and mechanical alloyed powders are compared. Mechanical alloying gives more homogeneous compositions and particle morphology, characterised by rounded, significantly enlarged particles. In the sintered samples alpha and beta phase are observed. The alpha phase appears at the grain boundaries and in lamellae growing inward from the edge, and is depleted in Nb. The b phase is enriched with Nb, Fe and Cr. The addition of Fe and Cr significantly increases the mechanical properties of Ti Nb alloys, providing increased ductility.This paper is based on a presentation at Euro PM 2014, organised by EPMA in Salzburg, Austria on 21-24 September 2014. This work was funded by UPV by the Staff Training Program for Predoctoral Researchers dated 28 February 2014. The Ministry of Science and Innovation of Spain by project research MAT2011-28492-C03 and Generalitat Valenciana by ACOMP / 2014/151.Amigó Mata, A.; Zambrano, JC.; Martínez, S.; Amigó Borrás, V. (2014). Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy. Powder Metallurgy. 57(5):316-319. https://doi.org/10.1179/0032589914Z.000000000210S316319575Niinomi, M. (1998). Mechanical properties of biomedical titanium alloys. Materials Science and Engineering: A, 243(1-2), 231-236. doi:10.1016/s0921-5093(97)00806-xWen, M., Wen, C., Hodgson, P., & Li, Y. (2014). Fabrication of Ti–Nb–Ag alloy via powder metallurgy for biomedical applications. Materials & Design (1980-2015), 56, 629-634. doi:10.1016/j.matdes.2013.11.066Cremasco, A., Messias, A. D., Esposito, A. R., Duek, E. A. de R., & Caram, R. (2011). Effects of alloying elements on the cytotoxic response of titanium alloys. Materials Science and Engineering: C, 31(5), 833-839. doi:10.1016/j.msec.2010.12.013Kuroda, D., Niinomi, M., Morinaga, M., Kato, Y., & Yashiro, T. (1998). Design and mechanical properties of new β type titanium alloys for implant materials. Materials Science and Engineering: A, 243(1-2), 244-249. doi:10.1016/s0921-5093(97)00808-3Málek, J., Hnilica, F., Veselý, J., & Smola, B. (2013). Heat treatment and mechanical properties of powder metallurgy processed Ti–35.5Nb–5.7Ta beta-titanium alloy. Materials Characterization, 84, 225-231. doi:10.1016/j.matchar.2013.08.006Boyer R, Welsch G and Collings E: ‘Materials properties handbook: titanium alloys’; 1994, Materials Park, OH, ASM International.Yang, Y. L., Wang, W. Q., Li, F. L., Li, W. Q., & Zhang, Y. Q. (2009). The Effect of Aluminum Equivalent and Molybdenum Equivalent on the Mechanical Properties of High Strength and High Toughness Titanium Alloys. Materials Science Forum, 618-619, 169-172. doi:10.4028/www.scientific.net/msf.618-619.169Terayama, A., Fuyama, N., Yamashita, Y., Ishizaki, I., & Kyogoku, H. (2013). Fabrication of Ti–Nb alloys by powder metallurgy process and their shape memory characteristics. Journal of Alloys and Compounds, 577, S408-S412. doi:10.1016/j.jallcom.2011.12.166Liu, Y., Chen, L. F., Tang, H. P., Liu, C. T., Liu, B., & Huang, B. Y. (2006). Design of powder metallurgy titanium alloys and composites. Materials Science and Engineering: A, 418(1-2), 25-35. doi:10.1016/j.msea.2005.10.057Bidaux, J.-E., Closuit, C., Rodriguez-Arbaizar, M., Zufferey, D., & Carreño-Morelli, E. (2013). Metal injection moulding of low modulus Ti–Nb alloys for biomedical applications. Powder Metallurgy, 56(4), 263-266. doi:10.1179/0032589913z.000000000118Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2014). Titanium carbide precipitation in Ti–22Nb alloy fabricated by metal injection moulding. Powder Metallurgy, 57(1), 2-4. doi:10.1179/0032589914z.000000000153Zou, L. M., Yang, C., Long, Y., Xiao, Z. Y., & Li, Y. Y. (2012). Fabrication of biomedical Ti–35Nb–7Zr–5Ta alloys by mechanical alloying and spark plasma sintering. Powder Metallurgy, 55(1), 65-70. doi:10.1179/1743290111y.0000000021Suryanarayana, C. (2001). Mechanical alloying and milling. Progress in Materials Science, 46(1-2), 1-184. doi:10.1016/s0079-6425(99)00010-9EN ISO-3325·2000: ‘Sintered metal materials, excluding hardmetals. Determination of transverse rupture strength’.Afonso, C. R. M., Aleixo, G. T., Ramirez, A. J., & Caram, R. (2007). Influence of cooling rate on microstructure of Ti–Nb alloy for orthopedic implants. Materials Science and Engineering: C, 27(4), 908-913. doi:10.1016/j.msec.2006.11.001Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2013). Microstructure and mechanical behavior of metal injection molded Ti–Nb binary alloys as biomedical material. Journal of the Mechanical Behavior of Biomedical Materials, 28, 171-182. doi:10.1016/j.jmbbm.2013.08.013Angelo PC and Subramanian R: ‘Powder metallurgy: science, technology and applications’, 1–5, 105–109, 132–133; 2009, New Delhi, PHI Learning.Lee, C. M., Ju, C. P., & Chern Lin, J. H. (2002). Structure-property relationship of cast Ti-Nb alloys. Journal of Oral Rehabilitation, 29(4), 314-322. doi:10.1046/j.1365-2842.2002.00825.xLagos, M. A., & Agote, I. (2013). SPS synthesis and consolidation of TiAl alloys from elemental powders: Microstructure evolution. Intermetallics, 36, 51-56. doi:10.1016/j.intermet.2013.01.006Majumdar, P., Singh, S. B., & Chakraborty, M. (2008). Elastic modulus of biomedical titanium alloys by nano-indentation and ultrasonic techniques—A comparative study. Materials Science and Engineering: A, 489(1-2), 419-425. doi:10.1016/j.msea.2007.12.029Kim, H.-S., Kim, W.-Y., & Lim, S.-H. (2006). Microstructure and elastic modulus of Ti–Nb–Si ternary alloys for biomedical applications. Scripta Materialia, 54(5), 887-891. doi:10.1016/j.scriptamat.2005.11.001Souza, S. A., Manicardi, R. B., Ferrandini, P. L., Afonso, C. R. M., Ramirez, A. J., & Caram, R. (2010). Effect of the addition of Ta on microstructure and properties of Ti–Nb alloys. Journal of Alloys and Compounds, 504(2), 330-340. doi:10.1016/j.jallcom.2010.05.13

Recent advances in laser surface treatment of titanium alloys

This paper reviews progress over the last five years in the field of laser surface modification of titanium alloys. The authors analyze the effect of new laser technologies and new materials as tools for improving surface properties-specifically, biocompatibility and resistance to wear, corrosion, and high temperatures. The authors discuss the effect of laser processing parameters on the microstructure and compare the results obtained by various researchers. Therefore, an overview of the difficulties involved in the laser processing of titanium is provided with a discussion of future prospects. © 2011 Laser Institute of America.The authors wish to acknowledge the Spanish Ministry of Science and Innovation for funding this research through Project No. MAT2008-06882-C04-04 (part of the national minerals program). The authors also wish to acknowledge the support of the Generalitat Valenciana through Project No. ACOMP/2009/232. The translation of this paper was funded by the Universidad Politecnica de Valencia, SpainCandel Bou, JJ.; Amigó Borrás, V. (2011). Recent advances in laser surface treatment of titanium alloys. Journal of Laser Applications. 23(2):1-7. https://doi.org/10.2351/1.3574020S1723

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

Mechanical properties of duplex stainless steel laser joints

[EN] This work presents the influence of welding parameters on the microstructural parameters and mechanical behaviour of welded joints. In doing so, we seek to establish the microstructural changes in the molten area and the heat affected zone, which will define the mechanical properties of the welded joints. This mechanical behaviour is evaluated by means of traction tests on welded test pieces and microhardness scanning of the heat affected zone.The authors would like to express their gratitude to the Asociación de Investigación de Óptica de la Comunidad Valenciana [Community of Valencia Optics Research Association] for the application of the laser welds and to the Spanish Ministry of Science and Technology for its support through Project MAT2001-1123-C03-02.Amigó, V.; Bonache Bezares, V.; Teruel Biosca, L.; Vicente-Escuder, Á. (2006). Mechanical properties of duplex stainless steel laser joints. Welding International. 20(5):361-366. doi:10.1533/wint.2006.3582S36136620

Fatigue behaviour of GMAW welded aluminium alloy AA7020

[EN] The aim of this investigation is to evaluate the influence on fatigue behaviour of the finishing of the bulge in a welded aluminium zinc magnesium alloy AA7020. It was determined that total or partial elimination of the bulge has very little influence on its behaviour, giving a very similar result on both cases, where one is better than the other by only 3%.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Vicente-Escuder, Á. (2009). Fatigue behaviour of GMAW welded aluminium alloy AA7020. Welding International. 23(10):111-116. doi:10.1080/09507110902843321S111116231

Microstructural evolution and mechanical properties of in-situ as-cast beta titanium matrix composites

[EN] The aim of this research is to investigate the effects of B4C additions on microstructure refinement and mechanical properties, due to in-situ formation of TiB and TiC in a matrix of beta titanium by casting process. Researches have been done on the individual effects of TiC and TiB compounds in titanium composites, however, their hybrid effect has been scarcely explored in beta titanium alloys. The effects on lattice parameter were investigated by Rietveld refinement and EDS analysis. The beta lattice parameters increased due reaction between Ti and B4C. DTA analysis revealed the sequence of phase formation on heating and cooling around the melting point, being confirmed by investigation of orientation relationship between phases by EBSD and pole figure analysis. Orientation relationships are {312}(TiB)//{112}(beta), {112}(TiC)//{112}(beta) for the smallest addition of B4C, {113}(TiC)//{112}(beta) for the remaining composites, and {010}(Ti)(B)//{011}(T)(i)(c) between the particles. Grain size reduced by half with 0.5% addition of B4C, while 3% addition made grains 25 times smaller than the alloy. Young's modulus and hardness increased with the addition of boron carbide. An analysis of the hardness of the materials was carried out from a nano to a macro scale. The as-cast composite materials have a refined structure with improved mechanical properties in comparison to the commercial alloy. (C) 2018 Elsevier B.V. All rights reserved.The authors gratefully acknowledge the Brazilian research funding agencies CNPq (National Council for Scientific and Technological Development) and CAPES (Federal Agency for the Support and Evaluation of Graduate Education) for their partial financial support of this work.Rielli, VV.; Amigó, V.; Contieri, RJ. (2019). Microstructural evolution and mechanical properties of in-situ as-cast beta titanium matrix composites. Journal of Alloys and Compounds. 778:186-196. https://doi.org/10.1016/j.jallcom.2018.11.093S18619677

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

Study of Electrochemical and Biological Characteristics of As-Cast Ti-Nb-Zr-Ta System Based on Its Microstructure

[EN] The quaternary Ti-Nb-Zr-Ta (TNZT) alloy was successfully cast-fabricated with the objective to be used in the medical field. Samples' microstructure was compared to CP-Ti and Ti-6Al-4V (control samples) and related to corrosion, ion release and biological properties. As-cast TNZT was formed with large grain sizes (285 m) compared to the ultrafine grain sizes of CP-Ti (11 m) and the + ultrafine grain sizes of 1.45 m and 0.74 m. Hardness and flexural elastic moduli (94 HV and 43 GPa) came close to the biological structures, such as dentin and enamel values. The ion release mechanism of as-cast TNZT was significantly lesser than CP-Ti and Ti-6Al-4V, which can be related to the difference in samples¿ grain sizes and chemical compositions. However, the corrosion rate was higher than for the control samples; this way offers corrosion properties inferior with respect to the properties obtained in the reference materials. Biological assays demonstrated that the two-cell (hDPSCs and MG-63) lineage studied presented good adhesion and capability to differentiate in bone cells on the as-cast TNZT surface, and no cytotoxicity effects were found. Details and reasons based on samples¿ microstructure are discussed.The authors thank the Spanish Ministerio de Economia y Competitividad for Research Project RTI2018-097810-B-I00 and the European Commission for FEDER funds.Correa Rossi, M.; Navarro, B.; Milian Medina, L.; Vicente-Escuder, Á.; Amigó, V. (2022). Study of Electrochemical and Biological Characteristics of As-Cast Ti-Nb-Zr-Ta System Based on Its Microstructure. Metals. 12(3):1-25. https://doi.org/10.3390/met1203047612512

Corrosion behaviour of Ti6Al4V ELI nanotubes for biomedical applications

[EN] Surfaces engineering on titanium biomedical alloys aiming for improving bone regeneration, healing periods and increasing lifetime needs fora fundamental understanding of the electrochemical reactions occurring at the interface biomaterial/human fluid. There, electrochemical corrosion plays an important role in implant-tissue interaction. The aim of this study is to investigate the effect of different TiO2 surfaces and nanotubes on a Ti6Al4V ELI in their electrochemical corrosion resistance by different electrochemical techniques (open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization). The electrochemical behaviour of native, anodized, nanotubular and annealed nanotubular surfaces were investigated in 1 M NaCl solution. The nanotubular topography was obtained by electrochemical oxidation and the annealing treatment allowed at changing the crystalline structure of the oxides. The nanotube morphology, chemical composition, and structure was studied by Field Emission Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-ray diffraction and Transmission Electron Microscopy respectively. The results show that the anodic oxidation treatment creates a nanotubular topography that increases the surface area and changes the surface chemical composition. The electrochemical corrosion resistance decreased on the as-formed TiO2 tubes compared to the native oxide layer, due to higher surface area and amorphous crystal structure of the passive film. After annealing treatment, the fluoride ions are eliminated, and nanotubular resistance is enhanced through anatase stabilization.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, and the European Commission via FEDER funds to purchase equipment for research purposes and the Microscopy Service at the Valencia Polytechnic University. Thanks to Alba Dalmau and Javier Navarro Laboulais from Instituto de Seguridad Industrial y Medio Ambiente, Valencia Polytechnic University for the technical assistance with preparation of the electrochemical tests. Thanks to Irene Llorente and Jose Antonio Jimenez from CENIM/CSIC for the technical assistance with XRD characterization.Lario, J.; Viera, M.; Vicente-Escuder, Á.; Igual Muñoz, AN.; Amigó, V. (2019). Corrosion behaviour of Ti6Al4V ELI nanotubes for biomedical applications. Journal of Materials Research and Technology. 8(6):5548-5556. https://doi.org/10.1016/j.jmrt.2019.09.023S554855568