The scientific study of fingerprints/fingermarks—dactyloscopy—is one of the most important fields in forensic science today. Fingermarks are amongst the most common type of evidence recovered from crime scenes and are arguably the most valued due to the fact that they are, unlike deoxyribonucleic acid (DNA), completely unique to an individual. Fingermarks recovery techniques are constantly evolving and new reagents are always being sought. This project aims to develop and access new fingermark enhancement procedures. The efficacy of an ethanoic solution of phosphomolybdic acid, has been investigated as a latent fingermark enhancement reagent, primarily on porous substrates. After treating samples and exposing them to ultraviolet radiation, the phosphomolybdic acid solution was shown to develop fingermarks to a high quality. Unlike the common amino acid reagents used for the enhancement of fingermarks on porous substrates, ninhydrin and 1,8-diazafluoren-9-one, phosphomolybdic acid stains a range of other compounds found within fingermark deposits, including lipids. The lysochrome diazo dye Oil Red O was used for comparative purposes due to its application in staining some of the same components of fingermark residues that phosphomolybdic acid would be proposed for. Initial results indicate that phosphomolybdic acid is comparable to Oil Red O at developing fingermarks on porous surfaces and may also have applications on non-porous surfaces. A systematic evaluation of solvent carriers was conducted, and whilst many solvents were insufficient, others did show some potential. Primary alcohols such as ethanol, methanol and propan-1-ol all developed fingermarks with identifiable ridge detail. Attempts to mix phosphomolybdic acid with other reagents which react with different fingermark constituents than those phosphomolybdic acid targets were, for the most part unsuccessful. However, not entirely ruled out. Many substrates were tested to observe which developed fingermarks when treated with the phosphomolybdic acid solution. Whilst marks were detected on numerous substrates, paper proved to be the most receptive. Similar stains to the phosphomolybdic acid were tested under the same conditions, however, none were as effective as the phosphomolybdic acid. A non-destructive, non-invasive technique was developed, utilising cuprous metals and their reactions with rubeanic acid. By bringing substrates with fingermarks deposited upon their surface into contact with a copper or copper alloyed plate, it was possible to transfer the fingermark residues to the plate. Forensic gelatin lifters could then be used to lift the marks from the metal plates, these lifted marks could subsequently be treated with a rubeanic acid solution to visualise the fingermarks. The rubeanic acid reacted with the Cu(II) which had been transferred to the fingermark residues to produce a dark product in the pattern of fingermark ridges. The technique was successful at developing fingerprints on semi-porous substrates. The technique was as effective on non-porous substrates, such as glass, but an investigation into the process on porous surfaces was less positive. Attempts to reuse the cuprous metals for the transference of fingermarks after an initial lift resulted in double or ghosted marks being developed, after a thorough wash with soap and water. This was overcome by cleaning with the metal cleaner Brasso. Copper cleaned with Brasso was reused 5 times to show its effectiveness, and adverse effects were minimal. The UK s recent move to polymer banknotes has seen some of the currently used fingermark enhancement techniques for currency potentially become redundant, due to the substrate characteristics of the polymer surfaces. Possessing a non-porous surface with some semi-porous properties, alternate processes are required for polymer banknotes. A preliminary investigation was conducted in to the recovery of fingermarks from polymer notes via vacuum metal deposition using elemental copper. The study successfully demonstrated that fresh latent fingermarks, from an individual donor, could be clearly developed and imaged in the near infrared. By varying the deposition thickness of the copper, the contrast between the fingermark minutiae and the substrate could be readily optimised. Where the deposition thickness was thin enough to be visually indistinguishable, forensic gelatin lifters could be used to lift the fingermarks. These lifts could then be treated with rubeanic acid to produce a visually distinguishable mark. The technique has shown enough promise that it could be effectively utilised on other semi- and non-porous substrates. A follow up group study was less effective than the aforementioned initial study. Many samples were processed using the vacuum metal deposition; incorporating a comparison study between copper and the gold/zinc standard and a depletion trial. However, when imaging was attempted a week after treatment, the results experienced before were unable to be replicated. Attempts to recover samples of radioactive nickel isotope from metal substrates using forensic gel lifters were initially unexceptional. Wipe tests were more successful at recovering the isotope. Experimentation using some non-metallic substrates was more fruitful, the gel lifters were able to recover the radioisotope more readily. Autoradiography showed that, although a weak beta emitter, nickel could be imaged when in sufficient quantities. By using nickel and a short half-life isotope of phosphorus in conjunction with patterned stamps and patterned deposits it was possible to image these patterns by autoradiography of the gels used to lift from the substrates these were deposited upon. These autoradiography images showed enough detail to warrant attempts with a synthetic finger, however, the imaging was insufficient to image the fine details of the friction ridges. Fingermarks deposited on the surface of agar gels showed bacterial growth after incubation for 24 hours. Aseptic transfer of bacterial colonies to fresh agar plates in a typical streak pattern were fruitful. Further transference to a nutrient broth were effective, however, attempts to seed bacterial agar plates for use in inhibition tests were unsuccessful. Overall, phosphomolybdic acid proved to be relatively effective, being able to develop fingermarks on a number of substrates. The copper transfer method, although, less fruitful than PMA showed promise. This lead to the idea of gel lifting from copper VMD treated polymer banknotes which was much more effective. Although, the radioactive and biological techniques showed promise, they were unfortunately unsuccessful at developing fingermarks. A number of the techniques evaluated and developed were successful enough to be published in forensic journals.

Esta Tese descreve a preparação de novos eletrodos modificados (EMs) fazendo uso de um método novo, a deposição de partículas de metais nobres, como níquel, paládio e platina sobre partículas de metais comuns, como cobre e ferro. Este método leva aos denominados EMs mistos, que podem apresentar características diferentes e mais eficientes que os EMs Ni, Pd e Pt já estudados, sendo a principal aplicação nas reações de hidrogenação eletrocatalítica (HEC) de substratos orgânicos insaturados. A preparação dos EMs mistos se inicia pelo recobrimento da superfície do eletrodo de trabalho com um filme polimérico. O polímero usado foi o poli-(éter alílico do ácido p-benzenossulfônico), um filme aniônico com boa estabilidade química e mecânica, que pode fazer troca iônica de seus íons H+ por cátions metálicos. Este filme é preparado por varreduras de voltametria cíclica de uma solução do respectivo monômero, que se oxida eletroquimicamente iniciando a reação química de polimerização. Os metais cobre e ferro são introduzidos ao polímero pelo método de troca iônica/redução eletroquímica, onde o EM é mergulhado em uma solução saturada de um sal de cobre ou de ferro para ocorrer a troca iônica. Em seguida, estes íons são reduzidos eletroquimicamente por varreduras de voltametria cíclica, usando uma faixa de potencial adequada. Para se preparar os EMs mistos, mergulhou-se estes EMs (Cu ou Fe) na solução do banho electroless de níquel, paládio e platina. Por esta metodologia partículas destes metais nobres são depositadas pelo processo de deposição metálica electroless (DME), que faz uso de um agente redutor, hipofosfito de sódio, para reduzir os íons destes metais de forma adequada nos EMs Cu ou Fe e onde se espera obter grande área superficial. Os EMs mistos preparados foram: Cu/Ni, Cu/Pd, Cu/Pt, Fe/Ni, Fe/Pd e Fe/Pt. A caracterização dos metais dos EMs mistos foi feita indiretamente por geração eletroquímica de hidrogênio (GH) de uma solução ácida e diretamente pelas técnicas de Difração de Raios X e Microscopia de Varredura Eletrônica (MEV). O processo de deposição metálica foi investigado por medidas de potencial de circuito aberto, realizadas durante a deposição dos metais nobres que indicou a ocorrência do processo de DME em alguns casos e DG (deposição galvânica) em outros. Devido a alguns resultados do processo de deposição metálica, foi estudado o mecanismo de catalise na deposição direta das partículas de níquel, paládio e platina pela redução química por hipofosfito dos íons correspondentes. Preparou-se EMs Ni, Pd e Pt por dois métodos: troca iônica/redução eletroquímica e troca iônica/redução química catalisada pelo filme. Estes foram caracterizados por GH e utilizando o ácido p-toluenossulfônico como modelo, estudos de espectroscopia na região UV/Vis. foram realizados. Estas medidas comprovaram a catálise, pois os EMs preparados por redução química apresentaram melhores resultados para a GH e as análises de UV/Vis. mostraram a forte ligação existente entre os grupos sulfonatos do polímero e os íons metálicos bivalentes, ligação essencial para ocorrer a catálise do filme. Verificou-se que as partículas dos metais nobres podiam estar sendo depositadas por DME ou por DG seguido de DME, mas que em todos os casos ocorria a deposição causada pela catálise do filme. A reatividade dos EMs mistos foi avaliada por um estudo cinético, onde HECs de alguns substratos orgânicos foram realizadas e acompanhadas por medidas de UV/Vis. durante as reações. Obteve-se a constante de velocidade (k) destas reações, as quais foram comparadas entre si e encontrou-se como o EM misto mais eficiente o Cu/Pt. As ks das reações deste EM foram comparadas com ks de outros EMs de Pt, já estudados em nossos laboratórios. / This thesis describes the preparation of new modified electrodes (MEs) using the method of noble metal particles deposition like nickel, palladium and platinum in the surface of commum metals particles as cooper and iron. This new electrodes were denominated mixed MEs, and can show different caractheristics and present higher efficiency than others already studied, being their principal application in electrocatalytic hydrogenation (ECH) of unsaturated organic substrates. The surface electrode were coated with the polymer poly-(ether allyl p-benzenesulfonic), an anionic film with good chemical and mechanic stability that can undergoes ion exchange of ions H+ by metallic cations. This film is prepared by anodic oxidation of the monomer using voltammetric cycles, producing a cation radical initiador of a chain reaction polymerization. Cooper and iron metals are incorporated in the polymer by ion exchange/ electrochemical reduction; the ME were dipped in saturated solution of cooper or iron salt to produce the ion exchange. The ions are then electrochemically reduced. The preparation of mixed MEs is carried out by electrolessly deposidated Ni, Pd or Pt. This methodology use NaH2PO2, to reduce the metal ions. This procedure deposits Ni, Pd and Pt in the surface of Cu or Fe MEs with an expected higher superficial area. The mixed Cu/Ni, Cu/Pd, Cu/Pt, Fe/Ni, Fe/Pd e Fe/Pt MEs were prepared. The characterization of the MEs metals was made indirectly by electrochemically hydrogen generation from an acid solution (HG) and directly by SEM-EDX and Ray X Diffraction analysis. The metallic deposition process was investigated by open circuit during the deposition of nobles metals that indicate the occurrence of electroless deposition (EMD) process in some cases or spontaneous displacement reaction (galvanic deposition - GD) in others. Despite the two mechanisms related above, a catalytic process would occur. To rut in evidence this third process Ni, Pd and Pt MEs were prepared by two methods: ion exchange/electrochemical reduction and ion exchange/chemical reduction catalyzed by the film. The resulting MEs were characterized by HG and spectroscopy in the UV/Vis. For this last analysis, p-toluenossulfonic acid was used as model and the results proved the catalytic mechanism. UV spectroscopy analysis showed strong bonds between the p-toluenossulfonic and the noble metal salts. So particles of noble metals can be deposited not only by EMD or GD but in all cases occur the deposition by film catalysis too. The reactivity of mixed MEs was done by kinetic study, where ECH of some organic substrates were carried out and monitored by UV/Vis spectroscopy. The constant rate (k) of the reactions was calculated and compared with the others mixed MEs. The ks of this ME were compared with the ks of other Pt MEs, already studied. The more reactive of them was the Cu/Pt ME.

Additive manufacturing (AM) is a general name used for manufacturing methods which have the capabilities of producing components directly from 3D computeraided design (CAD) data by adding material layer-by-layer until a final componentis achieved. Included here are powder bed technologies, laminated object manufacturing and deposition technologies. The latter technology is used in this study. Laser Metal Powder Deposition (LMPD) is an AM method which builds components by fusing metallic powder together with a metallic substrate, using a laser as energy source. The powder is supplied to the melt-pool, which is created by the laser, through a powder nozzle which can be lateral or coaxial. Both the powder nozzle and laser are mounted on a guiding system, normally a computer numerical control (CNC) machine or a robot. LMPD has lately gained attentionas a manufacturing method which can add features to semi-finished components or as a repair method. LMPD introduce a low heat input compared to conventional arc welding methods and is therefore well suited in, for instance, repair of sensitive parts where too much heating compromises the integrity of the part. The main part of this study has been focused on correlating the main process parameters to effects found in the material which in this project is the superalloy Alloy 718. It has been found that the most influential process parameters are the laser power, scanning speed, powder feeding rate and powder standoff distance.These process parameters have a significant effect on the temperature history ofthe material which, among others, affects the grain structure, phase transformation, and cracking susceptibility of the material. To further understand the effects found in the material, temperature measurements has been conducted using a temperature measurement method developed and evaluated in this project. This method utilizes a thin stainless steel sheet to shield the thermocouple from the laser light. This has proved to reduce the influence of the laser energy absorbed by the thermocouples.

The Atlantis II Deep is a location of modern submarine hydrothermal activity along the slowly spreading Red Sea rift axis. Venting of high-temperature hydrothermal fluids, similar to those associated with black smokers, takes place in a brine pool and has led to the accumulation of 90 Mt (dry, salt free) of stratiform, metalliferous sediment. The conditions of mineralization are unique in the modern oceans, but have been widely suggested as a possible analog of some important ancient stratiform base metal ore deposits. This study shows that many of the proposed genetic models for these ancient deposits may be highly simplified and do not take into account rapid diagenetic transformations, widespread non-equilibrium processes, and many other aspects of metal deposition. Sediment cores of the Atlantis II muds were last studied more than 30 years ago. High-resolution sampling and careful re-examination of the mineralogy and geochemistry of the sediments, using modern analytical techniques has significantly improved the understanding of the different processes responsible for the formation of the finely layered metallifeous sediments. The geochemistry of the individual layers is controlled by highly variable detrital, hydrogenic and hydrothermal input. Primary depositional pathways from the brine pool are the main control on basin-wide metal distribution (e.g., increasing Cu/Zn away from the vents) including variable enrichment in trace metals via scavenging from the brine pool and from the enriched pore waters. Cu and Zn have been deposited not only as sulfides but also with poorly crystalline Si-Fe-(oxy)hydroxides. A significant proportion of the original non-sulfide Cu and Zn are diagenetically transformed into sulfides, but also carbonates and clays, in large part reflecting sulfide deficient pore waters. Negative δ34S values, previously unrecognized in the sulfide- and metal-rich units, indicate a source of bacteriogenic sulfide. Syn-diagenetic processes also appear to have been responsible for the sharp laminations in the sediments, as well as distinctive zoning of carbonate and clay minerals around the vent source. The early diagenetic transformations observed in the Atlantis II Deep may not be preserved in the ancient rock record but nevertheless have important implications for metal deposition in some of the world’s largest and richest base metal ore deposits.

The challenges in the deposition of dissimilar materials are mainly related to the large differences in the physical and chemical properties of the deposited and substrate materials. These differences readily cause residual stresses and intermetallic phases. This has led to the development of functionally graded materials which exhibit spatial variation in composition. Laser direct metal deposition due to its flexibility, it offers wide variety of dissimilar and functionally graded materials deposition. Despite considerable advances in process optimization, there is a rather limited understanding of the role of metallurgical factors in the laser deposition of dissimilar and functionally graded alloys. The aim of this work is to understand and explain mechanisms occurring in diode laser deposition of dissimilar materials and functionally graded materials. The first part of this work addressed diode laser deposition of Inconel 718 nickel alloy to Ti-6Al-4V titanium alloy. Here, the effect of laser pulse parameters and powder mass flow rates on the stress formation and cracking has evaluated by experiment and numerical techniques. Results showed that the clad thickness was an important factor affecting the cracking behaviour. In the second part of this study, an image analysis technique has been developed to measure the surface disturbance and the melt pool cross section size during laser direct metal deposition of Inconel 718 on a Ti-6Al-4V thin wall. It was noted that under tested conditions the overall melt pool area increased with the increase in powder flow rate; the powder carrier gas flow rates also seemed to play important roles in determining the melt pool size. In the third part of this study, a parametric study on the development of Inconel 718 and Stainless steel 316L continuously graded structure has been carried out. Results suggested that microstructure and other mechanical properties can be selectively controlled across the deposited wall. The results presented in this dissertation can be used as a metallurgical basis for further development of dissimilar and functionally graded manufacturing using LDMD technique, guiding future manufacturing engineers to produce structurally sound and microstructurally desirable laser deposited samples.

Additive manufacturing (AM) is a general name used for production methodswhich have the capabilities of producing components directly from 3D computeraided design (CAD) data by adding material layer-by-layer until a final component is achieved. Included here are powder bed technologies, laminated object manufacturing and deposition technologies. The latter technology is used in this study.Laser metal deposition using powder as an additive (LMD-p) is an AM processwhich uses a multi-axis computer numerical control (CNC) machine or robot toguide the laser beam and powder nozzle over the deposition surface. Thecomponent is built by depositing adjacent beads layer by layer until thecomponent is completed. LMD-p has lately gained attention as a manufacturing method which can add features to semi-finished components or as a repair method. LMD-p introduce a low heat input compared to arc welding methods and is therefore well suited in applications where a low heat input is of an essence. For instance, in repair of sensitive parts where too much heating compromises the integrity of the part.The main part of this study has been focused on correlating the main processparameters to effects found in the material which in this project is the superalloy Alloy 718. It has been found that the most influential process parameters are the laser power, scanning speed, powder feeding rate and powder standoff distance and that these parameters has a significant effect on the dimensionalcharacteristics of the material such as height and width of a single deposit as wellas the straightness of the top surface and the penetration depth.To further understand the effects found in the material, temperaturemeasurements has been conducted using a temperature measurement methoddeveloped and evaluated in this project. This method utilizes a thin stainless steel sheet to shield the thermocouple from the laser light. This has proved to reduce the influence of the emitted laser light on the thermocouples.

Additive manufacturing of titanium and other metals is a rapidly growing field that could potentially improve component manufacturing through optimization of geometries, less material waste and fewer process steps. Although powder-based additive manufacturing processes have so far been predominant, methods using a wire as feedstock has gained popularity due to faster deposition rates and lower porosity in deposited material. The titanium alloy Ti-6Al-4V accounts for the majority of aerospace titanium alloy consumption and as titanium is a precious and expensive resource, reducing material waste is an important factor.  Laser metal deposition with wire (LMD-w) is currently used in production at GKN Aerospace in Trolhättan. One important process parameter is the oxygen level in the chamber during deposition as titanium is highly reactive with oxygen at process temperatures. Oxygen enrichment of titanium can cause embrittlement and reduced fatigue life due to formation of alpha-case, an oxygen enriched region directly beneath the surface. The oxygen level in the chamber is controlled through extensive use of protective inert gas which is a costly and time-consuming practice. The objective of this thesis was to study how elevated oxygen levels in the chamber would affect surface oxidation, chemical composition, tensile properties and microstructure.  Two different sample geometries were built with Ti-6Al-4V wire at an oxygen level of 100, 500 and 850 ppm. The subsequent analysis was based around microstructural features, alpha-case formation, chemical composition in surface layers, and tensile tests. Results showed that elevated oxygen levels in the build chamber did not degrade the chemical composition or tensile properties with regard to aerospace specifications. However, significant layers of alpha-case were found in all samples indicating that subsequent processing such as machining or etching is needed.

Laser metal deposition (LMD) offers a unique combination of process flexibility, time savings, and reduced cost in producing titanium alloy components. The current challenge in processing titanium alloys using LMD methods is understanding the complex microstructure evolution as a part is fabricated layer by layer. The current work focuses on the characterization, thermal, and microstructural modeling of multilayered Ti-6Al-4V deposits. A thermal model has been developed using finite difference techniques to predict the thermal history of LMD processes. A microstructure model that predicts the alpha phase fraction and morphology evolution was constructed to quantify the effect of thermal cycling on the as-deposited microstructure evolution. Alpha dissolution and growth are modeled assuming one-dimensional plate dissolution according to a parabolic rate law, and a Johnson-Mehl-Avrami-Kolmorgorov (JMAK) nucleation and growth model, respectively. Alpha morphology (colony-alpha and basketweave-alpha) evolution is tracked using a simplistic approach. Characterization of the deposit has shown that a complex microstructure evolves consisting of a two distinct regions: a transient region of undeveloped microstructure and a characteristic layer that is periodically repeated throughout the deposit. The transient region contains a fine basketweave and colony-alpha morphology. The characteristic layer contains a two phase mixture of alpha+beta, with the alpha phase exhibits regions of colony-alpha (layer band) and basketweave-alpha morphology. The different regions of microstructural contrast in the deposit are associated with thermal cycling. The thermal model results show that a heat affected zone defined by the beta transus extends approximately 3 layers into the deposit. The phase fraction model predicts the greatest variation in microstructural evolution to occur in a layer n after the deposition of layer n+3. The results of the morphology model show that increased amounts of colony-alpha form near the top of a characteristic layer. It follows that a layer band (colony-alpha region) forms as a result of heating a region of material to a peak temperature just below the beta transus, where a large amount of primary-alpha dissolves. Upon cooling, colony-alpha forms intragranularly. The coupled thermal and microstructure models offer a way to quantitatively map microstructure during LMD processing of Ti-6Al-4V. / Ph. D.

Depuis 1984, les matériaux à gradients de fonction (FGM) permettent de former une barrière thermique et réduire les fortes discontinuités des propriétés entre deux matériaux de nature différente. Ces multi-matériaux, qui consistent en une variation intentionnelle de la composition chimique entrainant par conséquent une modification des propriétés microstructurales, chimiques, mécaniques et thermiques, permettent de lisser la distribution des contraintes thermiques. L’élaboration in situ de ces alliages sur mesure est rendu possible grâce à l’utilisation de procédés de fabrication additive tel que le procédé par dépôt de poudres DED-CLAD®. Ces procédés connaissent un essor considérable depuis les années 1980 et sont idéaux dans la fabrication de FGM. Dans le cadre de cette thèse CIFRE, des développements techniques ont été effectués pour adapter le procédé DED-CLAD® et permettre la réalisation de FGM. Grâce à plusieurs collaborations industrielles, une étude complète a été réalisée sur les alliages titane-molybdène et titane-niobium. Ces alliages permettent dans le premier cas de réaliser des pièces résistantes à de fortes sollicitations thermiques (secteur spatial), et dans le second cas d’associer les propriétés mécaniques et la biocompatibilité (secteur biomédical). L’originalité de cette thèse repose sur l’étude d’un gradient complet, c’est-à-dire que l’ajout en élément d’alliage varie de 0% à 100%. En effet, les études reportées dans la littérature ne font pas mentions des alliages titane-matériaux réfractaire pour des taux élevés en élément réfractaire. Les analyses microstructurale (DRX, structure cristallographique par EBSD, microstructure), chimique (EDS) et mécanique (microdureté, tests de traction et essais d’indentation instrumentée) ont mis en évidence une évolution des propriétés le long du gradients de composition. La caractérisation mécanique des échantillons par indentation instrumentée s’est par ailleurs révélée particulièrement pertinente dans les cas de ces multi-matériaux / Since 1984, the Functionally Graded Material (FGM) allow to create a thermal barrier and to reduce the strong discontinuities of properties between two materials of different composition. These multimaterials,whose consist of an intentional variation in the chemical composition and, consequently, modify the microstructural, chemical, mechanical and thermal properties, lead to a smooth distribution of the thermal stress. The in-situ development of these custom-made alloys is made possible by the use of additive manufacturing processes such as the DED-CLAD® powder deposition process. These processes have grown substantially since the 1980s and are optimal for the manufacture of FGM. During this industrial thesis, technical developments have been carried out to adapt the DED-CLAD® process and to allow the manufacturing of FGM. Thanks to two industrial collaborations, a full study was carried out on titanium-molybdenum and titanium-niobium alloys. These alloys make it possible, in the first case, to produce parts resistant to strong thermal stress (space sector), and in the second case to combine mechanical properties and biocompatibility (biomedical sector). The originality of this thesis rests on the study of a complete gradient, that is the addition in alloy element varied from 0% to 100%. In fact, studies reported in the literature do not mention titanium-refractory material for high levels of refractory element. Microstructural (XRD, crystallographic analysis by EBSD technique), chemical (EDS) and mechanical (microhardness, tensile test and instrumented indentation) analyses revealed an evolution of the properties along the chemical gradient. The mechanical characterization of the sample by instrumented indentation has also proved particularly relevant in the case of these multi-materials

La fabrication additive est une famille de procédés permettant de construire des pièces finies, saines, de géométries très complexes, tout en diminuant le temps de développement des pièces, les coûts et les délais vis-à-vis des techniques de fabrication conventionnelles. Le point commun à tous ces procédés est de construire une pièce directement à partir des données CAO définissant sa géométrie sans outillage autre que la machine de fabrication additive.Cette thèse de Doctorat s'inscrit dans le projet de recherche FALAFEL (Fabrication Additive par procédé LAser et Faisceaux d’ÉLectrons) rassemblant les filières aéronautique et procédés laser dans le but de mettre en œuvre, d’améliorer et de valider des procédés de fabrication additive de pièces métalliques, dans des conditions industrielles et sur des composants aéronautiques.L'objectif est de proposer un modèle numérique permettant d’obtenir, dans des temps raisonnables, des informations sur les caractéristiques thermique, métallurgique et mécanique de pièces industrielles en titane Ti-6Al-4V destinées à être fabriquées par deux procédés de fabrication additive : la projection de poudre (Direct Metal Deposition ou DMD) et la fusion laser sélective (Selective Laser Melting ou SLM). / Additive manufacturing processes allow to build finished industrial parts with very complex geometry, while reducing development time and costs compared to conventional manufacturing processes. The main principle of all these processes is to build components directly from a CAD file defining its geometry without requiring any mold nor specific tools.This study is part of the FALAFEL research project focused on additive manufacturing processes by laser and electron beams. It is composed of academic research laboratories and industrial partners from Aeronautics and Laser Processes industries. The main goal of this project is to implement, improve and validate additive manufacturing processes regarding the production of metallic components for Aeronautics. Studies are conducted under industrial conditions.The aim of our thesis is to provide a numerical model to obtain, within a reasonable time, information about the mechanical and metallurgical properties of industrial components made out of titanium Ti-6Al-4V. It is aimed at two additive manufacturing processes: the Direct Metal Deposition (DMD) and the Selective laser melting (SLM).