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The development of metals tailored to the metallurgical conditions of laser-based additive manufacturing is crucial to advance the maturity of these materials for their use in structural applications. While efforts in this regard are being carried out around the globe, the use of high strength eutectic alloys have, so far, received minor attention, although previous works showed that rapid solidification techniques can result in ultrafine microstructures with excellent mechanical performance, albeit for small sample sizes. In the present work, a eutectic Ti-32.5Fe alloy has been produced by laser powder bed fusion aiming at exploiting rapid solidification and the capability to produce bulk ultrafine microstructures provided by this processing technique. Process energy densities between 160 J/mm³ and 180 J/mm³ resulted in a dense and crack-free material with an oxygen content of ~ 0.45 wt.% in which a hierarchical microstructure is formed by µm-sized ¿-Ti4Fe2Ox dendrites embedded in an ultrafine eutectic ß-Ti/TiFe matrix. The microstructure was studied three-dimensionally using near-field synchrotron ptychographic X-ray computed tomography with an actual spatial resolution down to 39 nm to analyse the morphology of the eutectic and dendritic structures as well as to quantify their mass density, size and distribution. Inter-lamellar spacings down to ~ 30–50 nm were achieved, revealing the potential of laser-based additive manufacturing to generate microstructures smaller than those obtained by classical rapid solidification techniques for bulk materials. The alloy was deformed at 600 °C under compressive loading up to a strain of ~ 30% without damage formation, resulting in a compressive yield stress of ~ 800 MPa. This study provides a first demonstration of the feasibility to produce eutectic Ti-Fe alloys with ultrafine microstructures by laser powder bed fusion that are suitable for structural applications at elevated temperature.

Applied materials today 20(100767), 1-11 (2020). doi:10.1016/j.apmt.2020.100767, The development of metals tailored to the metallurgical conditions of laser-based additive manufacturing is crucial to advance the maturity of these materials for their use in structural applications. While effort s in this regard are being carried out around the globe, the use of high strength eutectic alloys have, so far, received minor attention, although previous works showed that rapid solidification techniques can result in ultrafine microstructures with excellent mechanical performance, albeit for small sample sizes. In the present work, a eutectic Ti-32.5Fe alloy has been produced by laser powder bed fusion aiming at exploiting rapid solidification and the capability to produce bulk ultrafine microstructures provided by this processing technique. Process energy densities between 160 J/mm ³and 180 J/mm ³resulted in a dense and crack-free material with an oxygen content of ~0.45 wt.% in which a hierarchical microstructure is formed by μm-sized $η-Ti_4 Fe_ 2 O_ x$ dendrites embedded in an ultrafine eutectic $β$-Ti/TiFe matrix. The microstructure was stud- ied three-dimensionally using near-field synchrotron ptychographic X-ray computed tomography with an actual spatial resolution down to 39 nm to analyse the morphology of the eutectic and dendritic struc- tures as well as to quantify their mass density, size and distribution. Inter-lamellar spacings down to ~30–50 nm were achieved, revealing the potential of laser-based additive manufacturing to generate mi- crostructures smaller than those obtained by classical rapid solidification techniques for bulk materials. The alloy was deformed at 600 °C under compressive loading up to a strain of ~30% without damage formation, resulting in a compressive yield stress of ~800 MPa. This study provides a first demonstration of the feasibility to produce eutectic Ti-Fe alloys with ultra- fine microstructures by laser powder bed fusion that are suitable for structural applications at elevated temperature., Published by Elsevier, Amsterdam [u.a.]

Bacterial and fungal infections remain a major clinical challenge. Implant infections very often require complicated revision procedures that are troublesome to patients and costly to the healthcare system. Innovative approaches to tackle infections are urgently needed. We investigated the histological response of novel free P2O5 glass-ceramic rods implanted in the jaws of beagle dogs. Due to the particular percolated morphology of this glass-ceramic, the dissolution of the rods in the animal body environment and the immature bone formation during the fourth months of implantation maintained the integrity of the glass-ceramic rod. No clinical signs of inflammation took place in any of the beagle dogs during the four months of implantation. This new glass-ceramic biomaterial with inherent bactericidal and fungicidal properties can be considered as an appealing candidate for bone tissue engineering.

IMDEA - Materiales Two samples named ???57.3??? were measured by XCT (pre- and post- CO2 injection). The acquired volumes have been delivered to CIEMAT for their evaluation. The different phases are visible in XCT experiments and the differences from the two states are going to be evaluated by CIEMAT

The microstructural evolution as well as the damage mecha nisms and accumulation during RT tensile deformation of an AlSi12Cu5Ni2 piston alloy for high performance die sel truck engines are studied as a function of solution heat treatment (ST) time at 500°C. For this, interrupted in-situ synchrotron tomography experiments are combined with conventional metallography investigations. The study shows that the lower resistance to structural damage of the alloy after ST is linked to the local disintegration of the highly interconnected 3D network formed by intermetallics and Si embedded in the Al-matrix.

Two samples were measured by XCT (pre- and post- CO2 injection). The acquired volumes have been provided to CIEMAT for their evaluation. The different phases are visible in XCT experiments and the differences from the two states are going to be evaluated by CIEMAT- 35.4 Sample M1 and M2

Informe T??cnico IMDEA - Materiales Two samples were measured by XCT (pre??? and post??? CO2 injection). The samples investigated weer "Utrillas???62.45m". The acquired volumes have been delivered to CIEMAT for their evaluation. The different phases are visible in XCT experiments and the differences from the two states are going to be evaluated by CIEMAT.

In dieser Arbeit wurde die Anwendbarkeit der Mikrotomographie für Untersuchung des Kriechverhaltens und Kriechschädigung unter inhomogener Belastung beschrieben. Dazu wurde ein neues Verfahren zur Auswertung der Aktivierungsenergie des Kriechens entwickelt. Das Verfahren basiert auf "in situ" Überwachung einer einachsig beanspruchten Probe die eine lineare Temperaturverteilung entlang der Spannungsachse aufweist. Die mit der tomographischen Methode im rostfreien Stahl und Messing ermittelten Aktivierungsenergien stimmen gut mit Literaturdaten überein. Ferner wird die Verteilung der Kriechschädigung in einem mehrachsig beanspruchtem, gekerbtem Hohlzylinder aus E911-Stahl beschrieben. Die Analyse der Hohlraumverteilung zeigt die eingeschränkte Diffusion als dominierenden Mechanismus für Hohlraumswachstum. Es wird die Korrelation zwischen Verteilung der Schädigung, Spannungstriaxialität, Hauptspannung und der Von-Mises-Vergleichsspannung gesucht.

The use of composites materials in the industry has been strengthened in the last few years. In industries where materials with good specific mechanical properties are essential, the employment of composite materials has been promoted, highlighting the aeronautical, automotive, wind power and sports industries. However, the cost-per-part is still high rendering composite materials less attractive against other material options. Hence, it is crucial to keep on looking for either more economical manufacturing methods and/or optimising the current ones. Among the possible manufacturing methods, Liquid Composite Moulding (LCM) stands out due to its low cost and simplicity. However, the manufactured parts by LCM processes do not attain the quality (often measured by the amount of porosity in the part) obtained with other more expensive methods such as autoclave processing. In LCM-manufactured parts, a relatively high porosity is caused by mechanical entrapment of air when the resin is infiltrated into the dry fabric. Published investigations have confirmed that this entrapment is the result of a competition between capillary and viscous forces, which can be quantified by the modified capillary number. However, there is still much to learn about the mechanisms of void generation and transport in the different stages of the manufacturing process. In order to improve the knowledge about resin infiltration, void entrapment and transport, curing, etc. different techniques have been applied and reported in literature. Among those, one technique that stands out is X-ray tomography due to the ability to carry out inspections nondestructively and in three dimensions (3D), thus being able to look inside the composite material. These characteristics are used in this thesis to inspect in-situ the infiltration process, providing for the first time information about the infiltration and the phenomena of void formation and transport mechanism. For this purpose an in-situ set-up was developed. The study is divided into 3 different experiments, developed according to the tomographic technique employed: high-resolution tomography, laminography and fast-tomography. First of all, the fibre-resin system is characterised in order to be able to generalise any infiltration experiment by means of the modified capillary number. Resin viscosity and surface tension were characterized by rotational viscometer and modified Wilhelmy plate method, respectively, and the contact angle between resin and fibers was measured by high-resolution X-ray Computed Tomography (XCT). The contact angle results are compared with other contact angle measurements of the same or similar system (epoxy resin and E-glass fibres). With these three properties, the calculation of the modified capillary number is only dependent on the resin velocity. To gain the most benefit of high-resolution tomography, a wicking experiment was scanned at various heights when the resin reached equilibrium conditions. The XCT images allowed for analysing and quantifying the menisci formed between fibres in 3D. The shape of these menisci is directly related to the capillary pressure exerted by the interface gas-liquid since this pressure is a function of the mean curvature of the meniscus surface. In addition, the values of capillary pressure obtained from the extracted surfaces are similar to values found in literature and calculated with the Surface Evolver software. Following this characterisation, a low and an optimal velocity injection of epoxy resin into dry fibres are inspected in-situ by means of laminography. Several scans at different mould filling stages are presented. The laminography technique permits the inspection of wider moulds in comparison to standard XCT. The resin flow front within the fabric was observed in 3D with the laminographic images, allowing the calculation of the saturation profile as a function of time, quantification of void content during the infiltration process and visualising different void transport mechanisms. Additionally, the advantages and disadvantages of this technique are described. Finally, injections at low, optimal and fast resin velocity were inspected insitu by means of fast-tomography without blurring effects. With the tomographic images, the fibre impregnation and void formation processes of the three different regimes (capillary, viscous and optimal) were observed at high spatial and temporal resolutions. Variables such as saturation and void content were quantified during the measuring time. The capacity of observing the fabric inside allows for visualising in 3D the phenomena that impacts on the evolution of the quantified variables. ----------RESUMEN---------- El uso de materiales compuestos en la industria se ha potenciado en los últimos años. Industrias donde materiales con bajo peso y buenas propiedades mecánicas son fundamentales han fomentado su utilización, destacando la industria aeronáutica, automotriz, eólica y deportiva. Sin embargo, el alto precio por pieza puede restarle competitividad frente a otras opciones. Por tanto, se debe encontrar nuevos métodos de fabricación más económicos y / u optimizar los existentes. Entre los posibles métodos de fabricación destaca Liquid Composite Moulding (LCM) debido a su reducido coste y simpleza. Sin embargo, la calidad de los productos (a menudo se mide como la cantidad de porosidad dentro de la pieza) no alcanza la de otros métodos menos económicos como la fabricación por autoclave. En piezas fabricadas por LCM, una cantidad relativamente alta de porosidad es causada por el atrapamiento mecánico del aire que se produce cuando la resina se infiltra en la fibra seca. Investigaciones realizadas han confirmado que el atrapamiento de aire se debe a una competición entre las fuerzas capilares y viscosas, cuantificada por el número capilaridad modificado. Sin embargo, todavía hay mucho que aprender de los mecanismos de generación y transporte de poros en diferentes fases del proceso de fabricación. Para mejorar el conocimiento acerca de la infiltración de resina, atrapamiento y transporte de poros, curado, etc. se han aplicado distintas técnicas en diversos trabajos científicos. Entre ellos, destaca la técnica de tomografía de rayos X por su capacidad de realizar inspecciones no destructivas y en tres dimensiones (3D), permitiendo así observar el interior del material compuesto. Estas características se utilizan en esta tesis para inspeccionar in-situ el procedimiento de infiltración, por primera vez, aportando información acerca de los mecanismos de infiltración y de formación y transporte de poros. Para este fin, se ha desarrollado equipos para mediciones in-situ. El estudio se divide en 3 experimentos desarrollados de acuerdo a la técnica tomográfica utilizada: tomografía de alta resolución, laminografía y tomografía rápida. En primer lugar, se caracteriza el sistema fibra-resina para poder generalizar los resultados de cualquier infiltración mediante el número capilar modificado. La viscosidad de la resina y la tensión superficial se caracterizaron mediante un viscosímetro rotacional y el método de la placa de Wilhelmy respectivamente. El ángulo de contacto entre resina y fibras fue medido con tomografía computarizada de rayos X (XCT) de alta resolución. Los resultados obtenidos son comparables a los encontrados en la literatura para sistemas de resina epoxy y fibra de vidrio clase E. El conocimiento de estas tres propiedades permite calcular el número capilar en función solamente de la velocidad de la resina. Para sacar el mayor partido a la tomografía de alta resolución se inspeccionó a varias alturas un experimento de wicking cuando la resina alcanzó condiciones de equilibrio. Las imágenes obtenidas con XCT permitieron analizar y cuantificar los meniscos de resina que se forman entre fibras en 3D. La forma de estos meniscos está directamente relacionada con la presión de capilaridad ejercida por la interfaz líquido-gas, puesto que esta presión es función de la curvatura media de la superficie del menisco. Además, los valores obtenidos de las superficies extraídas se comparan con valores de presión capilar encontrados en literatura y con los valores obtenidos por el software Surface Evolver, obteniendo valores semejantes. Siguiendo esta caracterización, se inspeccionó in-situ una inyección a velocidad baja y otra a óptima de resina en fibra seca mediante la técnica de laminografía. Se realizaron varios escáneres en diferentes estados de llenado del molde. La técnica de laminografía permite la medición de moldes suficientemente anchos que eviten los efectos de borde. En estas se observó en 3D el frente del fluido dentro del tejido de fibras, se calculó la saturación frente al tiempo, se cuantificó la porosidad durante el proceso de infiltración y se visualizaron diferentes mecanismos de transporte de poros. Asimismo, se describen las ventajas y desventajas que ofrece la técnica propuesta. Finalmente, usando la técnica de tomografía rápida se inspeccionaron in-situ inyecciones de resina a baja, óptima y alta velocidad sin desenfoques de movimientos gracias a su bajo tiempo de medición. Con los resultados obtenidos, se observaron con alta resolución espacial y temporal los procesos de mojado de fibra y formación de poros según el tipo de régimen (capilar, óptimo y viscoso). Además, se cuantificó la evolución de variables como la saturación o el contenido de poros durante un periodo de tiempo. Al observar el interior del tejido de fibras, se visualizaron en 3D distintos fenómenos que influyen en la evolución de las variables cuantificadas.