This study deals with phase transformations in metastable β titanium alloys, focusing on the investigation of evolution of nanoparticles of thermodynamically metastable ω phase. For the purpose of this research, single crystals of two metastable β titanium alloys - LCB (Ti-6.8Mo-4.5Fe-1.5Al) and Ti-15Mo (in wt. %) - were grown in an optical floating zone furnace. It was established by differential scanning calorimetry that the phase transformations occurring in the material did not change significantly as a result of the single crystal growth process. Using single crystal X-ray diffraction, the shape and the size of ω particles were determined in a series of aged samples. The lattice parameters of ω particles and the β matrix, as well as the misfit between the two structures were calculated. The β phase was found to be locally deformed in compression around ω particles. Small-angle X-ray scattering (SAXS) experiments revealed a spatial ordering of ω particles in the β matrix in a disordered cubic array with the basis vectors along 100 β directions. The SAXS data also allowed the evaluation of the mean ω particle sizes and distances and confirmed that the ω particle growth obeys the t1/3 law following from the Lifshitz-Slyozov-Wagner theory. In situ SAXS performed during isothermal ageing at selected...

In this work phase transformations in metastable β (primarily Ti-15Mo) alloys were studied utilizing electrical resistance, dilatometry, transmission electron microscopy and X-ray and neutron diffraction. The materials Ti-15Mo, Ti-6.8Mo-4.5Fe-1.5Al (LCB), Ti-5Al-5V-5Mo-3Cr (Ti-5553), Ti-29Nb-1Fe-0.5Si (TNFS), Ti-15Mo-3Nb-3Al-0.2Si (Timetal 21S) and Ti-13Cr-1Fe-3Al (TCFA) (in wt. %) - were subjected to a solution treatment at a temperature above β transus and quenched into water. In this condition, the microstructure of the investigated materials consists of β matrix and ω particles. Samples quenched from important temperatures determined from in-situ electrical resistance and dilatometry measurements were studied by post-mortem TEM. In-situ X-ray and neutron diffraction provided direct observations of microstructure of Ti-15Mo alloy during linear heating and confirmed statements based on results of indirect methods, such as: the decrease of volume fraction of ω phase during heating at low temperatures (up to 250 ◦ C), complete dissolution of ω phase at 560 ◦ C and precipitation of α phase without ω particles serving as its direct precursors. X-ray diffraction experiment allowed to determine relative evolution of the size of ω particles while phase fraction evolution was derived from neutron diffraction. The...

La Gobernanza de las TI es una nueva filosofía de trabajo que se está integrando con fuerte aceptación a nivel organizacional. Las empresas sean estas públicas o privadas han visto en las tecnologías de la información (TI) la oportunidad de mejorar los procesos de forma automatizada. Sin embargo, a pesar de que las organizaciones están incluyendo en su infraestructura más sistemas de información, aún faltan controles por parte de la alta dirección organizacional que les permita medir de algún modo el adecuado uso de las TI, es decir, si las TI están generando valor organizacional y si están contribuyendo al logro de los objetivos del negocio. Lograr integrar las responsabilidades en la alta dirección para que se tomen decisiones sobre las TI es un trabajo difícil. Por ello en la actualidad se han creado normas y marcos de referencia que se han establecido para que la alta dirección tenga un modelo a seguir en base a principios de Gobernanza de las TI. Además de la responsabilidad que deben asumir los altos directivos sobre las decisiones y el uso adecuado de las TI desde el punto de vista estratégico, la Gobernanza de las TI se apoya en buenas prácticas proporcionadas por organizaciones que han visto mejores resultados al integrar estos procesos de buen gobierno. Una de estas prácticas es la implantación de una cartera de proyectos de TI, que permita alinear los proyectos que se van a ejecutar desde el punto de vista estratégico, permitiendo la optimización de recursos y generando mayor valor organizacional. El propósito de la tesis es poder contribuir a la implantación de una cultura de Gobernanza de las TI a través de una buena práctica probada. Para ello se ha realizado un estudio exhaustivo de la cartera de proyectos de TI, al segmentar esta buena práctica en elementos y ventajas que deban considerarse antes de su implantación. La investigación realizada en esta tesis permitirá tener a la mano una herramienta sencilla de utilizar con el fin de diseñar estratégicamente una cartera de proyectos de TI que incorpore elementos que puedan demostrar su claro alineamiento a los principios de Gobernanza de las TI. El aporte principal de la investigación es la propuesta de un instrumento para evaluar una cartera proyectos de TI (rúbrica de la CEPTIU), determinar si esta es estratégica y si está alineada a la Gobernanza de las TI. Esta rúbrica tiene 16 elementos considerados la parte tangible de la cartera. Adicionalmente se establecen 20 ventajas consideradas y relacionadas inicialmente como efecto de los elementos propuestos. Las ventajas son la percepción de hacer bien las cosas y de condiciones favorables en la organización. Adicionalmente en la propuesta se ha podido determinar la relación de alineamiento tanto lineal como transversal entre los elementos, ventajas y los principios de Gobernanza de las TI tomando como referente la norma internacional ISO/IEC 38500. Esta propuesta ha sido realizada para el entorno de las universidades españolas, sin embargo, puede tomarse de referencia en cualquier universidad pública del mundo con condiciones similares.

The most widely used titanium alloy in the hot sections of a jet engine is Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) and with the technological advancements additive manufacturing (AM) of Ti-6242 is of great interest. Although, there is not much published related to additively manufactured Ti-6242. The project aimed to provide an experimental input for simulations of additively manufactured,laser metal deposited–wire (LMD-w) of Ti-6242. The main part of this project has been to experimentally study the effect of isothermal temperatures and holding times on the microstructural changes in as-built Ti-6242 on Ti-64 base-plate. The evaluation of micro-structural changes with isothermal temperature, holding time and cooling rates on Ti-6242 are quantified in terms of alpha laths, phase fraction by using MIPAR (image analysis software) and preliminary determine mechanical properties by performing hardness tests.The microstructures obtained through a process are highly dependent on the thermal history is it exposed to and the mechanical properties are determined by the microstructures present. In this thesis work the alpha lath thickness and the hardness of the material increases with increasing isothermal temperature. From the phase fractions obtained forthe heat treated samples an equilibrium phase diagram and a TTT diagram is plotted for as-built microstructure.

[pt] O crescimento do setor de Tecnologia da Informação tem demandado a contratação de consultores dos quais são pretendidos elevados desempenhos e dedicação intensa ao trabalho. A satisfação no trabalho afeta diretamente a qualidade dos serviços prestados por estes consultores de TI. Desta forma, este estudo objetiva analisar a satisfação dos consultores do setor de TI de empresas brasileiras com algumas das dimensões do trabalho. Para tanto, foi realizada uma pesquisa quantitativa (survey) baseada no modelo Job Descriptive Index (SMITH et al., 1969) e coletados 158 questionários de empregados de consultorias de TI no Brasil. Concluímos que os consultores de TI no território brasileiro não estão satisfeitos com os salários que recebem nem com as oportunidades de promoção que as empregadoras oferecem. Por outro lado, eles sentem-se satisfeitos com as atividades laborais que exercem e com seus companheiros de equipe, mas são indiferentes quanto aos seus supervisores (incapazes de alimentar qualquer sentimento positivo ou negativo). Por fim identificamos também que não há evidências de que a satisfação com o salário e com as oportunidades de promoção interfira na satisfação com os supervisores e com a natureza do trabalho; e também não podemos afirmar que a satisfação com os companheiros de equipe afete a satisfação com as atividades laborais. / [en] The growth of the Information Technology sector has demanded the hiring of consultants from whom high performance and intense dedication to work are desired. Job satisfaction directly affects the quality of services provided by these IT consultants. In this way, this study aims to analyze the satisfaction of consultants in the IT sector of Brazilian companies with some of the work dimensions. A survey was conducted based on the Job Descriptive Index (SMITH et al., 1969) and 158 questionnaires were collected from IT consultants in Brazil. We conclude that IT consultants in Brazil are not satisfied with the salaries they receive, nor with the promotion opportunities offered by employers. On the other hand, they feel satisfied with the work activities they do and with their coworkers, but they are indifferent to their supervisors (unable to feed any positive or negative feelings). Finally, we also identify that there is no evidence that satisfaction with salary and promotion opportunities interferes with satisfaction with supervisors and the nature of work; And we cannot say that satisfaction with teammates affects satisfaction with work activities.

Fusion welding of dissimilar metals constitutes a crucial processing stage in a variety of applications, and the use of high energy beams (HEB) like lasers and electron beams for such welding applications has several advantages, such as, precision, narrow heat affected zone, and consequently, low distortion. An understanding of microstructural evolution in the weld is a prerequisite for producing sound joints with desired properties. HEB welding of similar metals have been studied extensively. In contrast, fewer studies have been directed toward understanding the fundamental aspects of solidification of dissimilar welds. This thesis presents an effort in that direction by exploring microstructural evolution in Ti/Ni dissimilar welds. Welding of Ti/Ni serves to illustrate the fundamental differences that distinguish dissimilar welding from the welding of similar metals. These are: (i) Thermophysical properties of the base metals are, in general, different, and this can have important consequences in the heat transfer conditions. (ii) Composition can vary over an wide range, the extreme being for the case of a pure binary couple, and the solid–liquid interface cannot be defined by a single liquidus isotherm. (iii) In addition to the surface energy driven Marangoni convection, a strong solutal convection can arise due to a large difference in the density of the base metals. (iv) Nucleation of phases assumes greater importance, especially in systems with intermediate phases. We have carried out laser and electron beam welding (LW and EBW) experiments in a butt welding geometry to join Ti/Ni dissimilar couples. Weld microstructures were characterised using scanning and transmission electron microscopy (SEM and TEM); composition information was obtained from energy dispersive spectroscopy (EDS) of Xrays in the SEM. In addition to the pure binary couple, we have also studied electron beam welding of Ti/Ni with a thin Ta interlayer. We summarise our findings in each set of experiments in the following sections. Laser welding of Ti/Ni We have studied partial penetration welds obtained within the range of experimental parameters used in our study. These welds show the following interesting features: 1. The welds are asymmetric with respect to the initial joint. Despite its higher melting point, Ti melts more than Ni due to its lower thermal diffusivity, making the average composition of the weld richer in Ti (Ti–40at.%Ni). 2. Composition changes very steeply near the fusion interfaces in both Ti and Ni with associated microstructural changes. The variation is of much lesser magnitude in the rest of the weld, reflecting a well mixed melt pool on a macroscopic scale. 3. Growth of base metal grains into the weld pool at the fusion interfaces is severely restricted at both Ti and Ni ends. 4. The Ti fusion interface is marked by a band consisting of Ti2Ni dendrites which grow toward the Ti base metal. 5. Layered structures form at the Ni fusion interface. The sequence of the layers is: solid solution (Ni)→ Ni3Ti→ Ni3Ti+NiTi eutectic → NiTi. We note the absence of the (Ni)+Ni3Ti eutectic in this sequence. 6. NiTi and Ti2Ni are the major phases that appear in the bulk of the weld. Volume fraction and morphology of NiTi vary almost periodically to form microstructural bands. 7. Solid state transformation of NiTi results in the formation of the Rphase and martensite, which reflect the composition heterogeneity in the weld. Sometimes, Ni4Ti3 precipitates are observed also, providing indirect evidence of nonequilibrium solidification. 8. Nitrogen pickup from the atmosphere during welding leads to the formation titanium nitride dendrites in the weld. 9. Solutal convection and buoyancy forces manifest themselves through the segregation of the lighter nitride and Ti2Ni phases toward the top surface of the weld; the heavier liquid forms blocky NiTi in the bottom half of the weld. These observations stand in striking contrast with the microstructures of conventional welds. We have proposed a set of composition and temperature profiles in the weld which reflect the diffusive and advective transport processes; when combined with thermodynamic information from the Ti–Ni phase diagram to yield spatial liquidus temperature profiles, these profiles can adequately explain most of the results. Our observations illustrate the importance of (a) nucleation, and (b) the inhomogeneous nature of the melt in which growth takes place. They also highlight the role of convective currents in bringing about local fluctuations in composition and temperature leading to ‘low velocity bands’. Electron beam welding of Ti/Ni We have carried out full penetration EBW of thin plates of Ti and Ni. The major observations are: (i) Average composition of the weld is in the Ni–rich side of the phase diagram (Ni–40at.%Ti). (ii) Fusion interface microstructures are very similar to that in LW exhibiting restricted base metal growth (although little amount of epitaxy can be seen in the Ni side), growth of Ti2Ni dendrites toward the base metal at the Ti fusion interface and the sequence of layers at the Ni interface: (Ni)→ Ni3Ti→ Ni3Ti+NiTi. Unlike LW, however, Ni3Ti, instead of NiTi, reappeared after the third layer on the Ni side. (iii) General microstructure consists of the Ni3Ti+NiTi eutectic, which appears in several anomalous as well as regular morphologies. (iv) Formation of NiTi is restricted mostly to regions near the Ti fusion interface. (v) Segregation of Ni3Ti was observed in a few places. The most prominent change in the microstructure compared to LW is a shift from the Ti2Ni– NiTi phases in the bulk of the weld to a Ni3Ti+NiTi eutectic structure. This is a direct consequence of the shift in the average composition of the weld to the Ni– rich side. The occurrence of different anomalous and regular eutectic structures bear similarity with bulk undercooling experiments conducted on eutectic systems having a strongly faceting phase as one of its constituents. The asymmetric coupled zone, along with composition and temperature fluctuation due to fluid flow, can be attributed to the origin of these structures. Electron beam welding of Ti/Ni with a Ta interlayer Motivated by the report of superior mechanical properties of Ti/Ni welds with an interlayer of Ta, whose melting point is much higher than those Ni and Ti, we performed EBW experiments using a Ni–Ta– Ti configuration. The key observations are: (i) The process is inherently unsteady in nature, and results in partial and irregular melting of the Ta interlayer. This partial melting essentially divides the weld into Ni–rich and Ti–rich halves. (ii) Microstructure near the fusion interface in Ni and Ti show similarities with that of the pure binary Ti/Ni welds; the phases here, however, contain Ta as a ternary addition. (iii) Microstructure in the Ti–rich half consists of dendrites of the Ni(Ti,Ta) phase with a high Ti:Ta ratio, and an eutectic formed between this phase and a (Ti,Ta)2Ni phase having significant amount of Ta. Two Ni(Ti,Ta) type phases dominate the microstructure in the Ni–rich half: the phase having a higher Ti:Ta ratio forms cells and dendrites, whereas the one of a lower Ti:Ta ratio creates an interdendritic network. (iv) Regions near the unmolten Ta layer in the middle show the formation of a sawtoothlike Ta–rich faceted phase of composition (Ta,Ti)3Ni2. Since very scarce thermodynamic data exist for the Ni–Ta–Ti ternary system, we have taken cues from the binary phase diagrams to understand the microstructural evolution. Such extrapolation, although successful to some extent, fails where phases which have no binary equivalents start to appear. In summary, in this thesis, we explore microstructural evolution in the Ti/Ni dissimilar welds under the different settings of laser and electron beam welding processes. This study reveals a variety of phenomena occurring during dissimilar welding which lead to the formation of an extensive range of microstructural features. Although a few questions do remain, most results can be rationalised by drawing from, and extending the knowledge gained from previous studies by introducing physical and thermodynamic arguments.

Cette étude s’inscrit dans le cadre du stockage de l’hydrogène pour des applications mobiles de faibles puissances électriques. Elle a été réalisée dans le cadre du projet FUI HyCAN. L’objectif était la formulation et la fonctionnalisation d’un alliage métallique de structure cubique corps centrée. Ces solutions solides désordonnées sont à base de vanadium qui présente initialement une bonne réactivité vis-à-vis de l’hydrogène.Cependant la thermodynamique du système V-H ne permet pas une utilisation pour des températures inférieures à 40°C, son coût est prohibitif et sa mise en oeuvre en milieu industriel nécessite quelques précautions. Nous avons travaillé sur trois grandes familles d’alliages à base de vanadium. Les alliages de Ti-V-Cr ont été étudiés au rayonnement synchrotron par diffraction X in operando dans le but de comprendre les transformations structurales observables lors de l’hydruration et de les relier à la thermodynamique des composés. Dans unsecond temps, le cahier des charges du projet nous a orienté vers des composites à base de vanadium dans lesquels nous développons une structure intergranulaire permettant une meilleure activation et une déstabilisation contrôlée de l’hydrure pour atteindre des températures de fonctionnement proche de 0°C.L’utilisation du ferro-vanadium en tant que précurseur a motivé l’étude des alliages de type Ti-V-Fe et Ti-V-Fe-Cr. La viabilité des solutions de stockage sur la base de ces matériaux est discutée. Tout au long de ces travaux la relation microstructure/propriété de sorption de l’hydrogène est systématiquement discutée et des modèles empiriques décrivant l’équilibre de l’hydrure sont systématiquement confrontés à la base bibliographique.Enfin, une partie de l’étude est consacrée à l’étude et à la modélisation des réservoirs en condition de fonctionnement, d’un point de vue de la thermique, du respect des normes de sécurité et des contraintes mécaniques générées par le lit de poudre réactif. / This study has been carried out in the framework of solid state hydrogen storage for mobile applications withlow electrical power. It was conducted under the FUI project HyCAN. The objective was to develop andfunctionalize a bcc alloy. Such disordered solid solutions are based on vanadium, which initially has a goodreactivity in relation to hydrogen. However, the thermodynamics of V-H system does not allow applicationsbelow 40 ° C, the cost is prohibitive and its implementation in industrial environments is not straightforward.We worked on three major families of vanadium alloys. Alloys Ti-V-Cr have been studied by in operandosynchrotron radiation X-ray diffraction in order to understand the observable structural transformations that takeplace during hydrogenation and then to link them to the thermodynamics of compounds. In a second step, thespecifications of the project directed us towards vanadium composites in which we develop an intergranularstructure for a better controlled activation and destabilization of the hydride so as to reach operatingtemperatures near 0 ° C. The use of ferro-vanadium as a precursor prompted the study of alloys in the Ti-V-Feand Ti-V-Cr-Fe systems. The viability of storage solutions on the basis of these materials is discussed.Throughout the course of this work the relationship between microstructure and hydrogen sorption properties issystematically discussed and empirical models describing the hydride equilibrium are routinely faced with thebibliographic database.Finally, part of the study is devoted to the study and modeling of reservoirs in operating condition, from thepoint of view of heat exchange, compliance with safety standards and mechanical stresses generated by the bedreactive powder.

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-12-04T11:52:46Z No. of bitstreams: 1 RobertaPintoCoelhoMacielPontesDissertacao2018.pdf: 2813246 bytes, checksum: 08608fe7fab4d1e6d8702fc959fccecb (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-12-04T11:52:57Z (GMT) No. of bitstreams: 1 RobertaPintoCoelhoMacielPontesDissertacao2018.pdf: 2813246 bytes, checksum: 08608fe7fab4d1e6d8702fc959fccecb (MD5) / Made available in DSpace on 2018-12-04T11:52:57Z (GMT). No. of bitstreams: 1 RobertaPintoCoelhoMacielPontesDissertacao2018.pdf: 2813246 bytes, checksum: 08608fe7fab4d1e6d8702fc959fccecb (MD5) Previous issue date: 2018-08-02 / The objective of this scientific research was to evaluate the strategic risks associated to IT Governance processes, using a specific method through which it was possible to measure the capability of these processes and to identify the associated risks, in an integrated way. The COBIT 5 PAM method was chosen to evaluate the processes and the scenario analysis tool was used to identify the risks. The method application was done in an institution and the processes selected for evaluation were the strategic level provided in COBIT 5, which composes the EMD domain. The risk identification was based on scenario analysis, using the results fixed in the PAM for capacity level 1 (in which the process is expected to fulfill its purpose) as an ideal scenario and as the actual scenario presented in the process evaluation. Aftering identified risks, they were submitted to a manager’s forum to be validated and prioritized. The result shows that the risk assessment method was efficient, as the risks were recognized by the managers. Also identified were the processes that need to be increased to mitigate the risks considered relevant were also identified. The direct association between processes, already evaluated in their capacities, and the resulting risks, already prioritized, allowed this simultaneous analysis. / O objetivo deste estudo foi avaliar os riscos estratégicos associados a processos de Governança de TI, utilizando um método próprio por intermédio do qual foi possível, de maneira integrada, mensurar a capacidade desses processos e levantar os riscos a eles associados. Foi escolhido o método PAM do COBIT 5 para avaliar os processos e utilizada a ferramenta análise de cenários para levantar os riscos. A aplicação do método foi feita numa instituição e os processos selecionados para avaliação foram os de nível estratégico previsto no COBIT 5, que compõe o domínio EMD. Já o levantamento dos riscos foi feito a partir de análise de cenário, utilizando como cenário ideal os resultados previstos no PAM para o nível de capacidade 1 (no qual está previsto que o processo cumpre a sua finalidade) e como cenário real aquele apresentado na avaliação do processo. Após os riscos levantados, eles foram submetidos a um fórum de gestores para serem validados e priorizados. O resultado demonstra que o método para levantamento de risco foi eficiente, na medida que os riscos foram reconhecidos pelos gestores. Foram também identificados os processos que precisam ser incrementados para mitigar os riscos considerados relevantes. A associação direta entre processos, já avaliados em suas capacidades, e os riscos decorrentes, já priorizados, permitiu esta análise simultânea.

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L'amélioration des performances spécifiques des alliages métalliques de l'aéronautique est une démarche constante. Les alliages de titane sont des matériaux privilégiés par les constructeurs aéronautiques car ils allient hautes propriétés mécaniques et faible densité.Parmi ces matériaux, les alliages β-métastables qui ont pour particularité de retenir jusqu'à 40% de phase β connaissent un fort regain d'intérêt pour les motoristes (Ti-17) comme pour des applications de structure type trains d'atterrissage (Ti-5553 et Ti-10-2-3). Ce travail a pour but d'analyser le comportement mécanique et la durabilité de ces alliages soumis à des sollicitations monotones et cycliques en lien avec les microstructures.Des essais mécaniques ont pour cela été développés à partir de différentes microstructures métallurgiques qu'elles soient issues d'un traitement industriel ou spécifique visant à simplifier ces dernières. Les mécanismes de déformation (systèmes de glissement) et d'endommagement (amorçage de fissures) ont été identifiés et analysés à différentes échelles par microcopie optique et électronique à balayage en intégrant les notions d'orientation cristallographique (EBSD). Le recours à des essais réalisés in situ sous microscope (optique et MEB) et à une métrologie adaptée aux échelles pertinentes a permis d'identifier les éléments micro-structuraux clés et les cinétiques de développement de ces processus. Un des faits marquants est le rôle majeur de l'anisotropie de propriétés mécaniques de la phase β qui a également fait l'objet de simulations numériques.