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

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

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

Use of rice straw ash as substitute of feldspar in triaxial porcelain

[EN] The substitution of raw materials for processing high energy consumption materials by agricultural and agro-industrial wastes causes a positive impacts on the environment preservation. One of these residues is rice straw, which according to FAO estimation, its annual production is about 600 million tons. In this research was studied the use of rice straw ash (RSA) as substitute of the use of feldspar in the whiteware production. Clay-feldspar-quartz porcelains are referred to as triaxial whiteware. Specimens of semidry triaxial mixtures, where feldspar was substituted for different percentages of CTA, were prepared by uniaxial pressing, followed by drying and sintering. Physical and mechanical properties of sintered bodies were evaluated. The porosity and the compressive strength of the fired pieces do increase with additions of up to 75% of CTA in substitution of feldspar. Their mineralogical phases were determined by DRX and SEM; grains of quartz, and needles of primary and secondary mullite were identified in a vitreous phase. It was concluded that feldspar can be substituted positively by CTA in whiteware pastes.[ES] La sustitución de materias primas para procesamiento de materiales -de alto consumo energético- por residuos agrícolas y agroindustriales impacta positivamente el medio ambiente. Uno de estos residuos es la paja o tamo de arroz, del cual la FAO estima que su disponibilidad mundial ronda los 600 millones de toneladas por año. En éste artículo se presentan los resultados de una investigación sobre la utilización de una ceniza de tamo o paja de arroz (CTA) como substituto del feldespato en la fabricación de cerámica blanca de tipo triaxial. Se prepararon mezclas donde la ceniza sustituyó al feldespato en volúmenes distintos. Especímenes de las pastas obtenidas fueron moldeados, secados, y cocidos. Se evaluaron las propiedades físicas y mecánicas de las cerámicas cocidas. La porosidad y la resistencia a la compresión de las piezas cocidas aumentan con adiciones de CTA de hasta un 75% en reemplazo del feldespato. Mediante DRX se estudió la evolución de las fases debido a la adición de CTA a la composición de la porcelana tradicional, y por MEB se estudió la microestructura, de granos de cuarzo y agujas de mullita primaria y secundaria en una matriz vítrea feldespática. Se concluyó que la CTA bajo las condiciones de obtención, sí reemplaza parcialmente al feldespato en la elaboración de pastas de loza.Los autores quieren agradecer a la Universidad del Valle (Colombia), al Instituto de Tecnología Cerámica (ITC), al Instituto de Tecnología de Materiales de la Universidad Politécnica de Valencia, al CENM y a COLCIENCIAS por el apoyo brindado para el desarrollo de este estudio. Se agradece a ECOS-Nord/COLCIENCIAS/ICFES/ICETEX por el apoyo a la Acción ECOS-Nord No. C09P01, en la cual se hicieron algunos ensayos de esta investigación. En particular, en esta publicación se presentan los resultados parciales de la investigación “Cerámicas Triaxiales basadas en Cenizas del Tamo de Arroz” código 110652128358 apoyada por COLCIENCIAS, Convocatoria 521 de 2010, contrato RC. No. 325-2011.Guzmán, Á.; Delvasto, S.; Sánchez, E.; Amigó Borrás, V. (2013). Cenizas del tamo de arroz como substituto del feldespato en la fabricación de cerámica blanca. Boletín de la Sociedad Española de Cerámica y Vidrio. 52(1):25-30. doi:10.3989/cyv.32013S253052

Stiffness variation of porous titanium developed using space holder method

The excellent properties of Ti have resulted in its generalised use for bone implants. However, Ti is very stiff in comparison with human cortical bone, and this creates problems of bone weakening and loosening of the implant. This article discusses the mechanical properties (flexural and compressive strength, and stiffness) of porous Ti-6Al-4V specimens developed using the space holder method. These properties are examined relative to the production process parameters: compacting pressure and sintering time, as well as temperature, and the addition of spacer and its particle size. It is seen that when spacer is added, compressive strength decreases with the application of compacting pressure and that these are the most influential parameters. The developed pieces show a closed and unconnected porosity. Small additions of spacer (25 vol.-%) reduce stiffness to around half of that shown by the solid material, and the resulting pieces are strong enough to be used as bone substitute. © 2011 Institute of Materials, Minerals and Mining.The authors wish to thank the Spanish Ministry of Science and Innovation for the support received under project no. PET2008_0158_02. The translation of this article was funded by the Universidad Politecnica de Valencia.Reig Cerdá, L.; Amigó Borrás, V.; Busquets Mataix, DJ.; Calero, JA. (2011). Stiffness variation of porous titanium developed using space holder method. Powder Metallurgy. 54(3):389-392. https://doi.org/10.1179/003258910X12707304455068S389392543RYAN, G., PANDIT, A., & APATSIDIS, D. (2006). Fabrication methods of porous metals for use in orthopaedic applications. Biomaterials, 27(13), 2651-2670. doi:10.1016/j.biomaterials.2005.12.002in ‘ASM handbook’, Vol. 2, ‘Properties and selection: nonferrous alloys and special-purpose materials’, 1170; 1990, Materials Park, OH, ASM International.Asaoka, K., & Kon, M. (2003). Sintered Porous Titanium and Titanium Alloys as Advanced Biomaterials. Materials Science Forum, 426-432, 3079-3084. doi:10.4028/www.scientific.net/msf.426-432.3079Niinomi, M. (2008). Mechanical biocompatibilities of titanium alloys for biomedical applications. Journal of the Mechanical Behavior of Biomedical Materials, 1(1), 30-42. doi:10.1016/j.jmbbm.2007.07.001Rack, H. J., & Qazi, J. I. (2006). Titanium alloys for biomedical applications. Materials Science and Engineering: C, 26(8), 1269-1277. doi:10.1016/j.msec.2005.08.032Köhl M, Bram M, Buckremer HP, Stöver D: Proc. Conf. Euro PM2007, Toulouse, France, October 2007, European Powder Metallurgy Association, 129–134.Bram M, Bogdanski SH, Koller M, Buchkremer HP, Stover D: Proc. Conf. Euro PM2005, Prague, Czech Republic, October 2005, European Powder Metallurgy Association, 517–522.Reig L, Amigó V, Busquets D, Salvador MD, Calero JA: Proc. Conf. Sintering 2008, La Jolla, CA, USA, November 2008, American Ceramic Society. 273–282.Degischer, H., & Kriszt, B. (Eds.). (2002). Handbook of Cellular Metals. doi:10.1002/3527600558Comín M, Peris JL, Prat JM, Decoz JR, Vera PM, JV: Hoyos: ‘Biomecánica de la fractura ósea y técnicas de reparación’, 66–69; 1999, Valencia, Publicaciones UPV.Gibson LJ, Ashby MF: ‘Cellular solids: structure and properties’, 175–231; 1999, Cambridge, Cambridge University Press.Making metal foams. (2000). Metal Foams, 6-23. doi:10.1016/b978-075067219-1/50004-0Esen, Z., & Bor, Ş. (2007). Processing of titanium foams using magnesium spacer particles. Scripta Materialia, 56(5), 341-344. doi:10.1016/j.scriptamat.2006.11.010Leyens, C., & Peters, M. (Eds.). (2003). Titanium and Titanium Alloys. doi:10.1002/3527602119Lütjering G, Williams JC: ‘Titanium’, 2nd edn, 13–51; 2007, Berlin, Springer, Engineering Materials and Processes

Estudio de la solidificación de recubrimientos de acero rápido M2 obtenidos por Laser Cladding

[EN] High speed steel laser cladding coatings are complex because cracks appear and the hardness is lower than expected. In this paper AISI M2 tool steel coatings on medium carbon AISI 1045 steel substrate have been manufactured and after laser cladding (LC) processing it has been applied a tempering heat treatment to reduce the amount of retained austenite and to precipitate secondary carbides. The study of metallurgical transformations by scanning electron microscopy (SEM) and backscattered electron diffraction (EBSD) shows that the microstructure is extremely fine and complex, with eutectic transformations and MC, M2C and M6C precipitation. Therefore, after the laser coating is necessary to use post-weld heat treatments.[ES] Los recubrimientos de acero rápido por Laser Cladding (LC) son complejos porque aparecen fisuras y la dureza es menor a la esperada. En este trabajo se han fabricado recubrimientos de acero AISI M2 sobre acero al carbono AISI 1045 y tras el procesado por láser, se han revenido para reducir la cantidad de austenita retenida y precipitar carburos secundarios. El estudio de las Transformaciones metalúrgicas con Microscopía Electrónica de Barrido (MEB) y Difracción de Electrones Retrodispersados (EBSD) muestra que la microestructura es extremadamente fina y Compleja, presenta transformaciones eutécticas y precipitación de carburos MC, M2C y M6C. Por tanto, tras el recubrimiento por láser es necesario recurrir a tratamientos térmicos post-soldeo.Candel Bou, JJ.; Franconetti Rodríguez, P.; Amigó Borrás, V. (2013). Study of the solidification of M2 high speed steel Laser Cladding coatings. Revista de Metalurgia. 49(5):369-377. doi:10.3989/revmetalm.1258S369377495Mesquita, R. A., & Barbosa, C. A. (2004). Spray forming high speed steel—properties and processing. Materials Science and Engineering: A, 383(1), 87-95. doi:10.1016/j.msea.2004.02.035Boccalini Jr, M., Corrêa, A. V. O., & Goldenstein, H. (1999). Rare earth metal induced modification ofγ-M2C,γ-M6C, andγ-MC eutectics in as cast M2 high speed steel. Materials Science and Technology, 15(6), 621-626. doi:10.1179/026708399101506355Serna, M. M., & Rossi, J. L. (2009). MC complex carbide in AISI M2 high-speed steel. Materials Letters, 63(8), 691-693. doi:10.1016/j.matlet.2008.11.035Benyounis, K. Y., Fakron, O. M., & Abboud, J. H. (2009). Rapid solidification of M2 high-speed steel by laser melting. Materials & Design, 30(3), 674-678. doi:10.1016/j.matdes.2008.05.030Godec, M., Batič, B. Š., Mandrino, D., Nagode, A., Leskovšek, V., Škapin, S. D., & Jenko, M. (2010). Characterization of the carbides and the martensite phase in powder-metallurgy high-speed steel. Materials Characterization, 61(4), 452-458. doi:10.1016/j.matchar.2010.02.003Hetzner, D. W., & Van Geertruyden, W. (2008). Crystallography and metallography of carbides in high alloy steels. Materials Characterization, 59(7), 825-841. doi:10.1016/j.matchar.2007.07.005Riabkina-Fishman, M., Rabkin, E., Levin, P., Frage, N., Dariel, M. ., Weisheit, A., … Mordike, B. . (2001). Laser produced functionally graded tungsten carbide coatings on M2 high-speed tool steel. Materials Science and Engineering: A, 302(1), 106-114. doi:10.1016/s0921-5093(00)01361-

Effect of process variables on the flexural behavior of alloys Ti - 3% at. X (X = Nb, Ta) obtained by powder metallurgy

[ES] El niobio y el tantalio se añaden al titanio para formar nuevas aleaciones beta con mayor biocompatibilidad para aplicaciones biomédicas. Ambos elementos tienen un elevado punto de fusión, por lo que su difusión en estado sólido es limitada. En este trabajo se han fabricado por pulvimetalurgia muestras de titanio con 3% atómico de niobio o tantalio. Se estudia el efecto de la presión de compactación, la temperatura y el tiempo de sinterizado sobre la resistencia, la elasticidad y la ductilidad a flexión. Los resultados muestran que ambos elementos se comportan de manera semejante: aumenta la resistencia entre 20-25%, la elasticidad entre 0-10% y la ductilidad en más de un 150%. Por tanto, la adición de estos elementos es beneficiosa para las propiedades mecánicas. El análisis estadístico muestra que el efecto de la temperatura y presión son importantes mientras que el efecto del tiempo es poco significativo e incluso perjudicial en estas aleaciones.[EN] Niobium and tantalum are added to titanium alloys to form new beta alloys with higher biocompatibility for biomedical applications. Both elements have a high melting point, that is the reason for their limited solid state diffusion. In this work samples of titanium with 3% at. niobium and tantalum have been manufactured by powder metallurgy. The effect of the compacting pressure, temperature and the sintering time on the strength, elasticity and ductility in bending has been studied. The results show that both elements behave similarly: flexural strength increases between 20-25%, elasticity between 0-10% and ductility over 150%. Therefore, the addition of these elements is beneficial to mechanical properties. Statistical analysis shows that the effect of temperature and pressure are important, while the effect of time is insignificant and even harmful in these alloys.Los autores agradecen al MINECO la financiación a través del programa de Formación de Personal Investigador con la ayuda BES-2009-013589 así como a través del proyecto de investigación bilateral con Brasil PIB2010BZ-00448. Este trabajo se ha desarrollado en la Unidad de Tecnología de Materiales de la Universidad Politécnica de Valencia asociada al CSIC a través del Centro Nacional de Investigaciones Metalúrgicas (CENIM). Por último, agradecer a la UE por la financiación recibida a través del FEDER en el proyecto UPOV08-3E-005 para la compra de equipamiento y a la Generalitat Valenciana por la ayuda ACOMP/2012/094.Franconetti Rodríguez, P.; Candel Bou, JJ.; Vicente-Escuder, Á.; Amigó Borrás, V. (2013). Efecto de las variables de proceso sobre el comportamiento a flexión de aleaciones Ti - 3% at. X (X = Nb, Ta) obtenidas por pulvimetalurgia. Revista de Metalurgia. 49(6):416-422. https://doi.org/10.3989/revmetalm.1259S416422496Scotchford, C. A., Cascone, M. G., Downes, S., & Giusti, P. (1998). Osteoblast responses to collagen-PVA bioartificial polymers in vitro: the effects of cross-linking method and collagen content. Biomaterials, 19(1-3), 1-11. doi:10.1016/s0142-9612(97)00236-6Popov, I., Starosvetsky, D., & Shechtman, D. (2000). Journal of Materials Science, 35(1), 1-8. doi:10.1023/a:1004734725783Esteban, P. G., Bolzoni, L., Ruiz-Navas, E. M., & Gordo, E. (2011). Introducción al procesado pulvimetalúrgico del titanio. Revista de Metalurgia, 47(2), 169-187. doi:10.3989/revmetalmadrid.0943Ivasishin, O. M., Eylon, D., Bondarchuk, V. I., & Savvakin, D. G. (2008). Diffusion during Powder Metallurgy Synthesis of Titanium Alloys. Defect and Diffusion Forum, 277, 177-185. doi:10.4028/www.scientific.net/ddf.277.177Benavente-Martínez, E., Devesa, F., & Amigó, V. (2010). Caracterización mecánica de aleaciones Ti-Nb mediante ensayos de flexión biaxial. Revista de Metalurgia, 46(Extra), 19-25. doi:10.3989/revmetalmadrid.02.1xiipmsPérez, R. A., Dyment, F., García Bermúdez, G., Abriola, D., & Behar, M. (2003). Diffusion of Ta in α-Ti. Applied Physics A: Materials Science & Processing, 76(2), 247-250. doi:10.1007/s00339020142

Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension

This study presents a criterion for predicting the martensitic variants (MVs) that appear during the stress-induced martensitic transformation (SIMT) in a polycrystalline sample of Cu 11.5% wt. Al 0.5% wt. Be under simple tension. Our criterion is based on crystallographic parameters, such as the crystal orientation and Schmid factor (SF). The displacement vector fields (DVFs) were obtained in the observation system by a mathematical model and were used to distort the boundary of a set of grains. From the DVF, the strain tensor for each grain was obtained, and the strain ratio (SR) in the observation system was calculated. Electron backscattering diffraction (EBSD) measurements were performed to determine the crystal orientation of the grains. The inverse SF was used to determine the in-plane stress transformation diagrams (STDs) for each studied grain. The combination of a balance criterion (BC) and STD provided a criterion that allowed us to predict the possible order of stress-induced MVs formed as a function of the crystal orientation and thermomechanical parameters of the shape memory alloy (SMA) with higher accuracy than when using the criteria separately. To validate our criteria, we tested other researchers published results. Our results were in agreement and were capable of predicting the stress-induced MVs in a polycrystalline SMA.The authors wish to thank the Coordinacion de estudios de posgrado (CEP)-UNAM, PAPIIT project number TI 02414 and Instituto de Tecnologia de Materiales-UPV for financial support. The authors are grateful to the Electron Microscopy Service of the UPV and especially to Manuel Josep Planes Insausti and Jose Luis Moya Lopez. The authors are grateful to Martin Estrada Arcos, Alberto Higuera Garcia, and Antonio Gonzalez Montaiio for their technical support.García Castillo, F.; Cortés Pérez, J.; Amigó Borrás, V.; Sánchez Arévalo, P.; Lara Rodríguez, G. (2015). Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension. Acta Materialia. 97:131-145. https://doi.org/10.1016/j.actamat.2015.06.044S1311459

Development of Ti–In alloys by powder metallurgy for application as dental biomaterial

Substantial progress has been made in Ti alloys’ properties and chemical composition. However, the effect of porosity and indium content on biocompatibility and corrosion behavior has not been sufficiently studied. Indium (In) is a promising nontoxic element that can replace other toxic elements, while porosity is associated with a good biological response. The purpose of this paper is to evaluate the achievability of three Ti–In alloys with 2.5, 5, and 10 wt.% Indium by powder metallurgy methods as dental prostheses. The findings of the present work showed that In acted as a grain refiner, and allowed us to obtain an 11.2-fold reduction for the Ti–10In sample than for the Ti–2.5In alloy. The total porosity of the Ti–In alloys decreased according to In content, however, grain size and In content showed a greater effect on the mechanical behavior in comparison with the effect of porosity, probably because of the low porosity percentage. All the mechanical values fell within the ranges accepted in the literature for dental implant applications. The Ti3+ and In3+ ion releases were below the toxic concentrations for the human body, with a maximum of 0.43 and 0.016 μg cm−2 h−1, respectively. Corrosion sensitivity decreased with In addition due to its surface protective effect on the Ti-matrix. These results proved that utilizing powder metallurgy methods, Ti–In alloys are feasible candidates for dental prosthesis. Of the three prepared Ti–In alloys, the Ti–10In alloy properties made it the most appropriate Ti–In alloy to be used as a dental implant

Caracterizacion morfologica y mecanica de nanofibras agregadas de PVA producidas por el proceso de sol-gel electrohilado

[EN] This work deals with the preparation of poly (vinyl alcohol) solutions composed of a surface active agent, an acid and water. With this solution firstly electrospun nanofiber mats and then nanofiber aggregates were obtained by electrospinning/sol-gel process. The samples were morphologically characterized using scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM), obtaining superficial roughness values, distribution and average diameter before and after the electrospinning/sol-gel process. The PVA nanofiber aggregate reached a maximum strength and a modulus of 90 MPa and 2.55 GPa, respectively. Experimental results show that these fibers have a potential use as secondary reinforcement materials in cementitious composites.[ES] En esta investigación se prepararon soluciones de Polivinil alcohol (PVA) dopadas con un agente surfactante, un ácido y agua. Con estas soluciones se electrohilaron en primer lugar, esteras de nanofibras y luego nanofibras agregadas a través del proceso de sol-gel electrohilado. Las muestras obtenidas fueron caracterizadas por microscopía electrónica de barrido (SEM) y microscopia de fuerza atómica (AFM), calculando valores de rugosidad superficial en las fibras, su distribución y diámetro promedio antes y después del proceso de solgel electrohilado. Finalmente, se encontró que las nanofibras agregadas de PVA, alcanzaron una resistencia máxima y módulo de 90 MPa y 2,55 GPa, respectivamente. Los resultados experimentales muestran que estas fibras tienen un uso potencial como refuerzo secundario en materiales compuestos cementicios.We appreciate the support of the Center of Excellence for New Materials (CENM) with equipment and supplies as well as the Composite Materials Group, of the School of Materials Engineering at the Universidad del Valle and the Universidad Politécnica de Valencia (Spain). Edgar Franco gratefully acknowledges the economic support of COLCIENCIAS through a doctoral fellowship.Franco Medina, E.; Delvasto Arjona, S.; Zuluaga Corrales, F.; Amigó Borrás, V. (2013). Morphological and mechanical response characterization of nanofiber aggregates of pva produced by electrospinning sol-gel process. DYNA.Revista de la Facultad de Minas de la Universidad Nacional de Colombia. Sede Medellin. 178(180):56-61. http://hdl.handle.net/10251/33978S566117818