Amorphous Mg-Cu-Y metallic glasses are established by density functional theory and simulated annealing method in this study. The mechanical properties of amorphous Mg-Cu-Y metallic glasses are investigated by molecular statics simulations for the nano-indentation and the nano-scratch process. In this study, some potential energy parameters are obtained by fitting for describing the Mg-Cu-Y system. The bulk modulus, the Young¡¦s modulus and X-ray structure of the Mg-Cu-Y system are calculated. Our results are within 10% error compared with experimental values, which prove the correctness of fitted potential parameters. For the cases of nanoindentations, the indentation force-displacement and the influenced depth are calculated. The mechanical properties are obtained are close to experimental results. The both ¡§slip vector¡¨ and Honeycutt-Andemen index (HA index) parameters are also used to study the deformation behavior and bond-type of a group of atoms. Our results indicate that the influenced depths can be affected by the tip indentation and the gather of copper atoms. The gather of copper atoms can provide the resistance and strengthen the mechanical properties of Mg-Cu-Y material. On the other hand, our results indicate that the amorphous structure of Mg-Cu-Y metallic glasses cannot be transferred to crystal structure during nano-indentation process by analysis of HA index. For the cases of nano-scratch, two different scratch depth (5Å and 15Å) are investigated to understand the understand the depth effect. the scratch force-displacement curve is also obtained. As the same with nano-indentation results, the scratch force will increase because the gather of copper atoms and provide the resistance.

The mechanical properties of the amorphous bulk metallic glassy (BMG) alloy, Mg58Cu31Y11, are examined by a non-traditional analytic method - nanoindentation scratch test. This thesis will discuss the influences of friction force, and fracture surface geometry on the BMG surface for load, depth of scratch, scratch velocity, and test temperature of the nano-scratch process. In this study, experimental factors, including load, depth of scratch, scratch velocity, and test temperature, are taken into consideration to investigate the effects of the friction force. And then, this research utilizes regression analysis to establish BMG machining experience formula. The significant parameters of the friction force on nano-scratch and the reliability of the prediction model are investigated by statistical software. According to the results, the friction force is nearly proportional to power of the load. The friction force exhibits a slightly dependence on the test temperature. Besides, the nano-scratch results show that the friction coefficient also increases as the load and test temperature increases. The results associated with the analysis of the variance can be practiced to assess the prominence among experimental factors. The analysis indicates that the load, test temperature play significant factors on the friction force. The results of the regression analysis using a statistical software can be applied to model the mathematical relationship between machining factors and friction force. It anticipates that the model is able to predict friction force over a wide variety of scratching conditions. The model is also proved in good agreement with experimental results.

L’évolution de la microélectronique suit plusieurs axes notamment la miniaturisation des éléments actifs (réduction de taille des transistors), et l’augmentation de la densité d’interconnexion qui se traduisent par la loi de Gordon Moore qui prédit que la densité d'intégration sur silicium doublerait tous les deux ans. Ces évolutions ont pour conséquence la réduction des prix et du poids des composants. L’hybridation ou flip chip est une technologie qui s’inscrit dans cette évolution, elle consiste en l’assemblage de matériaux hétérogènes. Dans cette étude il s‘agit d’un circuit de lecture Silicium et d’un circuit de détection InP ou GaAs assemblés par l’intermédiaire d’une matrice de billes d’indium. La connexion flip chip est basée sur l’utilisation d’une jonction par plots métalliques de faibles dimensions qui permet de diminuer les pertes électriques (faible inductance et faible bruit), une meilleure dissipation thermique, une bonne tenue mécanique. Enfin elle favorise la miniaturisation avec l’augmentation de la compacité et de la densité d’interconnexion.Les travaux de thèse se concentrent sur deux axes principaux. Le premier concerne l’hybridation par brasure avec la technologie des billes d’indium par refusion, et le second concerne l’hybridation par pression à température ambiante (nano-scratch) par l’intermédiaire des nanostructures (Nano-fils d’or, Nano-fils ZnO). Ces travaux ont permis la réalisation d’un détecteur InGaAs avec extension visible de format TV 640*512 pixels au pas de 15 µm. Ces travaux ont également permis la validation mécanique de l’assemblage d’un composant de format double TV 1280*1024 pixels au pas de 10 µm par cette même méthode de reflow. Pour l’axe hybridation à froid, nos travaux ont permis la validation d’une méthode de croissance de nano-fils ZnO par une voix hydrothermique à basse température (<90°C). / Evolution of microelectronics follows several major roads, in particular the size decrease of active elements (reduction of size of transistors), better electrical performances, high I/O density and smaller size. This revolution has been predicted by Gordon Moore who suggested that integrated circuits would double in complexity every 24 months. As a consequence, this evolution induces both the reduction of prices and the weight of components.The term flip chip describes the method of electrically connecting the die to the package substrate. Flip chip microelectronic assembly is the direct electrical connection of face-down (or flipped) integrated circuit (IC) chips onto substrates, circuit boards, or carriers, using conductive bumps on the chip bond pads. Flip chip offers the highest speed electrical performance, reduces the delaying inductance and capacitance of the connection, Smallest Size Greatest I/O Flexibility, Most Rugged, high I/O density and Lowest Cost.This thesis work study concentrates on two main directions. The first one concerns hybridization by means of the technology of Indium bumps associated to a reflow process and the second one is about pressure induced hybridization at low temperature using nanostructures (Nano-scratch). In this work, we have developed a complete process to assemble a focal plane array format of 640 x 512 pixels with a pitch of 15 µm. These studies also allowed the mechanical validation of hybridization of a focal plane arrays 1280*1024 pixels with a pitch of 10 µm. Concerning alternative technologies to flip chip reflow, we introduced and demonstrate the relevance of a method of growth of ZnO nanorods using low temperature wet chemical growth and further hybridization at ambient temperature.

L'évolution de la microélectronique suit plusieurs axes notamment la miniaturisation des éléments actifs (réduction de taille des transistors), et l'augmentation de la densité d'interconnexion qui se traduisent par la loi de Gordon Moore qui prédit que la densité d'intégration sur silicium doublerait tous les deux ans. Ces évolutions ont pour conséquence la réduction des prix et du poids des composants. L'hybridation ou flip chip est une technologie qui s'inscrit dans cette évolution, elle consiste en l'assemblage de matériaux hétérogènes. Dans cette étude il s'agit d'un circuit de lecture Silicium et d'un circuit de détection InP ou GaAs assemblés par l'intermédiaire d'une matrice de billes d'indium. La connexion flip chip est basée sur l'utilisation d'une jonction par plots métalliques de faibles dimensions qui permet de diminuer les pertes électriques (faible inductance et faible bruit), une meilleure dissipation thermique, une bonne tenue mécanique. Enfin elle favorise la miniaturisation avec l'augmentation de la compacité et de la densité d'interconnexion.Les travaux de thèse se concentrent sur deux axes principaux. Le premier concerne l'hybridation par brasure avec la technologie des billes d'indium par refusion, et le second concerne l'hybridation par pression à température ambiante (nano-scratch) par l'intermédiaire des nanostructures (Nano-fils d'or, Nano-fils ZnO). Ces travaux ont permis la réalisation d'un détecteur InGaAs avec extension visible de format TV 640*512 pixels au pas de 15 µm. Ces travaux ont également permis la validation mécanique de l'assemblage d'un composant de format double TV 1280*1024 pixels au pas de 10 µm par cette même méthode de reflow. Pour l'axe hybridation à froid, nos travaux ont permis la validation d'une méthode de croissance de nano-fils ZnO par une voix hydrothermique à basse température (<90°C).

Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer MoS2 on the SiO2/Si substrate is 7.78 J/m2. The practical adhesion energy was found to be an increasing function of the MoS2 thickness. Unlike SiO2/Si substrates, MoS2 films grown on the sapphire possess higher bonding energy, which is attributed to the defect-free growth and less number of grain boundaries, as well as less stress and strain stored at the interface owing to the similarity of Thermal Expansion Coefficient (TEC) between MoS2 films and sapphire substrate. Furthermore, we calculated the surface free energy of 2D MoS2 by the facile contact angle measurements and Neumann model fitting. A surface free energy ~85.3 mJ/m2 in few layers thick MoS2 manifests the hydrophilic nature of 2D MoS2. The high surface energy of MoS2 helps explain the good bonding strength at MoS2/substrate interface. This simple adhesion energy and surface energy measurement methodology could further apply to other TMDs for their widespread use.

Made available in DSpace on 2017-07-21T19:26:06Z (GMT). No. of bitstreams: 1 Bruna Corina Kurelo.pdf: 9097435 bytes, checksum: 9e2ea56fd2dfc2427ab47a5b071d8244 (MD5) Previous issue date: 2013-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nitriding by glow discharge (DL) and a new technique called luminous glow discharge with cathodic cage (DLGC) were techniques widely employed today for surface treatment. In the present work were investigated nanoscale tribo-mechanical properties of three grades:austenitic stainless steel (AISI 316), Martensitic (AISI 420) and supermartensitic (HP13Cr) subjected to treatments by DL and DLGC techniques. Martensitic steels have been previously heat-treated in 1025 C (AISI 420) and 1100C (HP13Cr) with subsequent rapid cooling in oil. The three classes of steels have been nitrided using the following parameters of temperature – time : 350 C/6 h, 400 C/6 h e 450 C/6 h (to DL and DLGC). The nitriding treatments were held in atmospheres of N2/H2 in the proportions of 20 %-80 % (in volume) to DL and 80 %-20 % (in volume) to DLGC. For the characterization of the samples were employed the techniques of x-ray diffraction (DRX), scanning electron microscopy (SEM), optical microscopy (OM), atomic force microscopy (AFM) and Energy Dispersive X-ray Spectrometry (EDS). The mechanical properties were evaluated by instrumented indentation (II), and, with the same equipment, the nano scratch tests. In the samples treated by DL the temperature influence the formation of different stages (γN or αN, γ'-Fe4N, ε-Fe2 + xN, CrN). In the treatments carried out at low temperature (350 C) the predominant phase formed is γN to austenitic steel AISI 316 and phases γ' and ε for martensitic steels HP13Cr and AISI 420, due to difference in solubility and diffusivity of nitrogen in the austenite and martensite phases.Nitriding treatments by DL cause the effect of chromium depletion to all steels in the temperature of 450°C. To DLGC treatments occurs the formation of ε phase regardless of temperature. By this way higher temperatures favor the formation of the phases γN and αN. In treatments by DLGC, hardness of the deposited layer measured by II remained, regardless of steel, next to that of the reference sample. The hardness of the modified layers existing below the films produced by DLGC is next the hardness of the layers produced by DL but no border effect and low roughness. In treatments by DL, the hardness increased from 2,5 GPa up to 15,5 GPa for steel AISI 316. The estimated thicknesses of modified surfaces treated by DL are superior to those of the layers deposited and modified by DLGC at same parameters. The scratch resistance of modified surfaces by DL increases to any conditions of treatment. The greatest value of critical load of scratch resistance obtained (126.7 ± 32.1 mN) for the layers deposited by DLGC is too low for typical applications expected of these steels. However, further analyzes are necessary in the modified layer to check the applicability of this technique for these steels.The conditions of excellence found for DL technique can provide an increase in the useful life of the parts treated in the media, where they are employed that require good mechanical and tribological properties. / Dentre as várias técnicas empregadas na atualidade para tratamento de superfícies, destaca-se a nitretação por Descarga Luminosa (DL) e uma nova técnica denominada nitretação iônica por DL com Gaiola Catódica (DLGC). No presente trabalho investiga-se as propriedades tribo-mecânicas em nanoescala de três classes de aços inoxidáveis: austenítico (AISI 316), martensítico (AISI 420) e supermartensítico (HP13Cr) submetidos a tratamentos pelas técnicas de DL e DLGC. Os aços martensíticos foram previamente tratados termicamente em 1025 °C (AISI 420) e 1100 °C (HP13Cr) com posterior resfriamento rápido em óleo. Os três aços foram nitretados nas seguintes condições de temperatura/tempo: 350 °C/6 h, 400 °C/6 h e 450 °C/6 h (DL e DLGC). As nitretações foram realizadas em atmosferas de N2/H2 nas proporções de 20 %-80 % para DL e 80 %-20 % para DLGC. As superfícies foram caracterizadas pelas técnicas de difração de raios X (DRX), microscopia eletrônica de varredura (MEV), microscopia de força atômica (MFA) e espectroscopia de raios X por energia dispersiva (EDS). As propriedades mecânicas foram avaliadas por indentação instrumentada (II), e, com o mesmo equipamento, realizaram-se os ensaios de nanorisco. Na técnica de DL ocorre influência da temperatura de tratamento na formação das diferentes fases (γN ou αN, γ’-Fe4N, ε- Fe2+xN, CrN); nos tratamentos realizados a baixa temperatura (350 °C) predomina a formação da fase γN para o aço austenítico AISI 316 e das fases γ’ e ε para os aços HP13Cr e AISI 420, de estrutura martensítica, devido a diferença de solubilidade e difusividade de nitrogênio nas diferentes fases austenita e martensita. Os tratamentos de nitretação por DL causam o efeito da depleção do cromo em quaisquer dos aços na temperatura de 450 C. Nos tratamentos por DLGC ocorre a formação da fase independentemente da temperatura. Entretanto temperaturas mais altas propiciam a formação das fases γN e αN. Nos tratamentos por DLGC, a dureza da camada depositada medida por II permaneceu, independentemente do aço, próxima à da amostra de eeferência. A dureza das camadas modificadas existentes abaixo dos filmes produzidos por DLGC é próxima a dureza das camadas produzidas por DL mas sem efeito de borda e com baixa rugosidade. Nos tratamentos por DL, a dureza elevou-se de 2,5 GPa a até 15,5 GPa para o aço AISI 316. As espessuras estimadas para as camadas modificadas de amostras tratadas por DL são superiores às das camadas depositadas e modificadas de amostras tratadas por DLGC nos mesmos parâmetros. A resistência ao risco das superfícies modificadas por DL aumenta para quaisquer condições de tratamento. O maior valor de carga crítica de resistência ao risco (126,7 ± 32,1 mN) obtido para as camadas depositadas por DLGC é um valor muito baixo para as aplicações típicas esperadas desses aços. No entanto, são necessárias análises complementares na camada modificada para verificar a aplicabilidade dessa técnica para estes aços. As condições de excelência encontradas para a técnica de DL podem proporcionar um aumento da vida útil das peças tratadas nos meios onde são empregadas que exigem boas propriedades mecânicas e tribológicas.

Le comportement mécanique du verre silico-sodo-calcique soumis à un contact ponctuel peut être amélioré par trempe. Les effets de trempe se manifestent par des gradients de propriétés sur le comportement du verre rendant la modélisation plus complexe. Ce travail a porté sur la modélisation et la simulation des verres non trempés et trempés soumis aux essais de nano-indentation et de nano-rayage. Les outils de simulation par éléments finis ont été développé et validés sur le verre métallique, choisi en raison de son comportement plastique connu. En comparant avec les données expérimentales, nous avons observé que les paramètres du matériau et les conditions expérimentales pouvaient donner la même réponse sur la courbe force-déplacement et l'empreinte. L’identification des propriétés du matériau doit être basée sur des comparaisons avec des simulations considérant la géométrie réelle de l'indenteur, la souplesse de la machine et le tilt de surface de l'échantillon. Les stratégies développées permettent de faire des identifications sur le comportement du verre silico-sodo-calcique. Dans la famille du verre silicaté, le verre silico-sodo-calcique a un comportement plastique semblable au verre de silice qui est affecté non seulement par le mécanisme de cisaillement mais aussi par la densification. Il est essentiel donc d'étudier le comportement densification/cisaillement du verre de silice car il est largement discuté dans la littérature. La comparaison des résultats de simulation par plusieurs modèles avec les courbes force-déplacement et les images d'empreinte a montré que la modélisation de la densification, en prenant en compte l'écrouissage et la modification des modules élastiques, est suffisante pour décrire le comportement des verres silicatés. Enfin, les connaissances sur les simulations des essais à chargement ponctuel et la modélisation du comportement du verre ont guidé une étude sur les effets du gradient de propriétés dans les verres trempées thermiquement et chimiquement. / The mechanical behavior of soda-lime-silica glass subjected to contact damage can be improved by tempering. The effects of tempering created tailor properties and the glass behavior more complicated. Therefore, this work studied the modeling and simulation of non-tempered and tempered glasses subjected to the nano-indentation and nano-scratch tests. The finite element simulation tools have been primarily validated and the metallic glass was chosen for the studies because of its known plastic behavior. By comparing with the experimental data, we have observed that the parameters of material model and the experimental conditions could give the same response on load displacement curve and imprint. The evaluation of material properties must be based on the comparisons with fully modeled simulation considering the real geometry of the indenter, the compliance of the instrument and the tilting of the sample surface. The developed strategies allow identification of soda-lime-silica glass behavior. Similar to that of silica glass, the plastic behavior of soda-lime-silica glass is not only affected by the shear mechanism but also the densification. Hence, it is essential to study the shear/densification behavior of silica glass as it is widely discussed in the literature. The comparison of simulation results by several models with the load displacement data and the images of imprint showed that the modeling of densification by taking into account the hardening and the change in elastic moduli is sufficient for describing the behavior of silicate glasses. Finally, the knowledge about the simulation of the contact loading tests and the modeling of glass behavior guided a study on the coupling of tailored properties effects in the thermally and chemically tempered glasses.