La technologie de projection plasma sous basse pression a attiré l’attention de nombreux chercheurs comme une nouvelle technique qui permet d’établir un pont entre la projection thermique conventionnelle et le dépôt physique en phase vapeur. Ainsi, cette technologie étend les limites de projection thermique classique et augmente également la vitesse de croissance des dépôts par rapport aux procédés PVD ou CVD classiques. Cette technique peut évaporer totalement ou partiellement les poudres injectées et mener à la réalisation de revêtements à microstructure colonnaire et/ou plus denses, difficiles à réaliser avec des procédés de projection thermique conventionnels. La projection plasma de suspension a été effectuée pour la première fois sous basse pression. L’injection axiale de suspension avec une torche tri-cathodes permet d’augmenter l’échange enthalpique entre le jet de plasma et les poudres après l’évaporation du solvant. La spectroscopie à l’émission optique (OES) a été utilisée pour estimer la température électronique et vérifier l’existence de phase vapeur d’YSZ dans le jet de plasma. Finalement, des revêtements plus denses furent réalisés (comparés à ceux préparés par projection plasma de suspension à pression atmosphérique présentant des particules fondues, agglomérées et de la condensation de vapeur. Des tests de nano-indentation instrumentée ont été effectués sur la surface polie des dépôts réalisés. Les résultats montrent des valeurs de 5,8 GPa pour la dureté et 114,5 GPa pour le module d’élasticité, augmentant de 61% et 31%, respectivement, en comparaison avec les valeurs obtenues par SPS sous atmosphère ambiante. Les essais de projection de poudre YSZ agglomérée ont été réalisés avec une torche F4-VB dans le but de synthétiser une phase vapeur d’YSZ. On observe que les dépôts peuvent se former derrière les échantillons en céramique, sans vis-à-vis du plasma, par condensation de vapeur. En face de cette torche, des revêtements composites ont été obtenus par un mélange de poudres fondues et condensation de vapeur, simultanément. Cependant la quantité de phase vapeur est très faible dans le jet de plasma. Pour comprimer ce jet sous basse pression et afin d’améliorer l’échange d’enthalpie entre le jet de plasma et les poudres injectées, une buse rallongée a été mise en place sur la torche F4-VB. Les revêtements présentent ainsi une microstructure plus dense. Ceci est attribué à la haute vitesse des particules fondues vers le substrat suite à l’utilisation de la buse modifiée. Ce type de revêtement montre une valeur maximale de microdureté Vickers de 1273 Hv100 g. Par ailleurs, la réalisation de dépôts de carbures a été effectuée. Les résultats montrent la possibilité de former des carbures par projection plasma sous basse pression. Les revêtements composites (TiC/Ti) sont déposés par projection plasma réactif sous basse pression en utilisant le méthane comme gaz porteur. La température électronique Te calculée est d’environ 6200 K selon les résultats d’OES, ce qui est supérieur à la température d’ébullition du Ti et de TiC. Le revêtement de Ti pur présente une microstructure dense alors que TiC/Ti présente une microstructure lamellaire. Cependant, la quantité de TiC dans les revêtements est d’environ 20 vol.%. La microdureté Vickers, effectuée sur surface polie, a tendance à diminuer de 846±152 à 773±86 Hv100 g avec l’augmentation de la distance de projection. / As a new technology, the very low pressure plasma spraying has attracted attentions of many researchers, making it possible to establish a bridge between the conventional atmospheric plasma spraying (APS) and the vapor deposition (PVD or CVD). As a result, this new technology enlarges the limitation of APS and increases the deposition rate in comparison with the PVD or CVD. It is possible to evaporate partially the injected material and even evaporate completely and finally realize the columnar or dense coatings from the vapor or the mixture of vapor and liquid. The suspension plasma spraying is performed for the first time at low pressure. Taking consideration of the configuration of the three-cathode torch, the axial injection of the suspension is conducted which can increase the enthalpy change between the plasma jet and the sprayed material. The data of optical emission spectroscopy (OES) could be used to calculate the electron temperature and verify the existence of vapor of YSZ in the plasma jet. Finally, the dense coating was prepared by suspension plasma spraying at low pressure, which is composed of the melted particles, the agglomerated particles and the vapor deposition. The test of nano-indentation is conducted on the polished surface. It shows a value of 5.8 GPa for the microhardness and 114.5 GPa for the elastic modulus, increasing 61% and 31%, respectively, compared with the values obtained by SPS in the ambient atmosphere. In this study, another torch F4-VB is also conducted even of it has a low power in compared with that of O3CP torch. The powder feed rate is reduced to about 1.5 g·min-1 to achieve the vapor of YSZ taking the low power input of the torch into consideration. The columnar structure coating is realized from vapor deposition out of line of sight of projection upon the ceramic tubes. The composite structure coating is deposited by the mixture of melted particles and the vapor deposition simultaneously in front of this torch. But the quantity of vapor of YSZ is low in plasma jet. In order to compress the larger plasma jet and then improve the enthalpy change between the plasma jet and sprayed particles, an extended nozzle is prepared. It shows that the coating has a dense structure, which can be attributed to higher velocity of the melted powders. The coating shows a maximum value of microhardness Vickers up to 1273 Hv100 g. The composite coating of TiC/ Ti is realized by reactive plasma spraying using the methane as the carrier gas. The electron temperature Te is calculated to be 6200 K, which is over the boiling point of TiC and Ti. The coating Ti shows a dense structure and the composite coating TiC/Ti shows a lamellar structure. But the quantity of TiC in the composite coating is very low, about 20 vol.%. The Vickers microhardness is performed on the polished surface. It shows a decreasing tendency from 846 ± 152 to 773 ± 86 Hv100g with the increase of spraying distance. The tribological test is also implemented showing a high value of the coefficient of friction of 0.78 to 0.85, which can lead to a high abrasion. In order to synthesize a larger quantity of TiC in the composite coating, a higher power input torch should be put into action in the future.

<p>Mechanical property and thermal stability of Zr-Si-N films of varying silicon contents deposited on Al₂O₃ (0001) substrates are characterized. All films provided for characterization were deposited by reactive DC magnetron sputter deposition technique from elemental Zr and Si targets in a N₂/Ar plasma at 800 ^oC. The hardness and microstructures of the as deposited films and post-annealed films up to 1100 ^oC are evaluated by means of nanoindentation, X-ray diffractometry and transmission electron microscopy. The Zr-Si-N films with 9.4 at.% Si exhibit hardness as high as 34 GPa and a strong (002) texture within which vertically elongated ZrN crystallites are embedded in a Si₃N₄ matrix. The hardness of these two dimensional nanocomposite films remains stable up to 1000 ^oC annealing temperatures which is in contrast to ZrN films where hardness degradation occurs already above 800 ^oC. The enhanced thermal stability is attributed to the presence of Si₃N₄ grain boundaries which act as efficient barriers to hinder the oxygen diffusion. X-ray amorphous or nanocrystalline structures are observed in Zr-Si-N films with silicon contents > 13.4 at.%. After the annealing treatments, crystalline phases such as ZrSi₂, ZrO₂ and Zr₂O are formed above 1000 ^oC in the Si-containing films while only zirconia crystallites are observed at 800 ^oC in pure ZrN films because oxygen acts as artifacts in the vacuum furnace. The structural, compositional and hardness comparison of as-deposited and annealed films reveal that the addition of silicon enhances the thermal stability compared to pure ZrN films and the hardness degradation stems from the formation of oxides at elevated temperatures.</p>

Mechanical property and thermal stability of Zr-Si-N films of varying silicon contents deposited on Al2O3 (0001) substrates are characterized. All films provided for characterization were deposited by reactive DC magnetron sputter deposition technique from elemental Zr and Si targets in a N2/Ar plasma at 800 oC. The hardness and microstructures of the as deposited films and post-annealed films up to 1100 oC are evaluated by means of nanoindentation, X-ray diffractometry and transmission electron microscopy. The Zr-Si-N films with 9.4 at.% Si exhibit hardness as high as 34 GPa and a strong (002) texture within which vertically elongated ZrN crystallites are embedded in a Si3N4 matrix. The hardness of these two dimensional nanocomposite films remains stable up to 1000 oC annealing temperatures which is in contrast to ZrN films where hardness degradation occurs already above 800 oC. The enhanced thermal stability is attributed to the presence of Si3N4 grain boundaries which act as efficient barriers to hinder the oxygen diffusion. X-ray amorphous or nanocrystalline structures are observed in Zr-Si-N films with silicon contents &gt; 13.4 at.%. After the annealing treatments, crystalline phases such as ZrSi2, ZrO2 and Zr2O are formed above 1000 oC in the Si-containing films while only zirconia crystallites are observed at 800 oC in pure ZrN films because oxygen acts as artifacts in the vacuum furnace. The structural, compositional and hardness comparison of as-deposited and annealed films reveal that the addition of silicon enhances the thermal stability compared to pure ZrN films and the hardness degradation stems from the formation of oxides at elevated temperatures.

Molding is a simple manufacturing process whereby fluid fills a master tool and then solidifies in the shape of the tool cavity. The precise nature of material flow during molding has long allowed fabrication of plastic components with sizes 1 mm 1 m. Polymer molding with precise critical dimension control could enable scalable, inexpensive production of micro- and nanostructures for functional or lithographic use. This dissertation reports experiments and simulations on molding of polymer micro- and nanostructures at length scales 1 nm 1 mm. The research investigates two main areas: 1) mass transport during micromolding and 2) polymer mechanical properties during nanomolding at length scales 100 nm. Measurements and simulations of molding features of size 100 nm 1 mm show local mold geometry modulates location and rate of polymer shear and determines fill time. Dimensionless ratios of mold geometry, polymer thickness, and bulk material and process properties can predict flow by viscous or capillary forces, shape of polymer deformation, and mold fill time. Measurements and simulations of molding at length scales 100 nm show the importance of nanoscale physical processes distinct from bulk during mechanical processing. Continuum simulations of atomic force microscope nanoindentation accurately model sub-continuum polymer mechanical response but highlight the need for nanoscale material property measurements to accurately model deformation shape. The development of temperature-controlled nanoindentation enables characterization of nanoscale material properties. Nanoscale uniaxial compression and squeeze flow measurements of glassy and viscoelastic polymer show film thickness determines polymer entanglement with cooperative polymer motions distinct from those observed in bulk. This research allows predictive design of molding processes and highlights the importance of nanoscale mechanical properties that could aid understanding of polymer physics.

The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory poly- mers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) study spin coating conditions on thin film quality with designed experiments. (iv) apply neural networks and genetic algorithms to optimize these systems.

Sn-Pb solder has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use and therefore many researchers are looking to replace it. Sn-3.0Ag-0.5Cu (SAC) solders are suggested as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) like Ag₃Sn and Cu₆Sn₅ have limited their use in high temperature applications. In this research work, RE elements, mostly lanthanum (La), are used as potential additives to SAC alloys. They reduce the surface free energy, refine the grain size and improve the mechanical and wetting properties of SAC alloys. An extensive experimental work has been performed on the microstructure evolution, bulk mechanical properties, individual phase (matrix and IMCs) mechanical properties, creep behavior and wettability performance of the SAC and SAC-La alloys, with different (La) doping. SEM and EDS have been used to follow the continuous growth of the IMCs at 150°C and 200°C and thus provide a quantitative measure in terms of their size, spacing and volume fraction. Grain size is measured at regular intervals starting from 10 hours up to 200 hours of thermal aging using Optical Microscope with cross polarized light. Bulk mechanical properties are evaluated using tensile tests at low strain rates. Individual phase mechanical properties like Young's modulus, hardness, strain rate sensitivity index and bulge effects are characterized with nanoindentation from 100 µN up to 5000 µN loadings at different temperatures of 25°C, 45°C, 65°C and 85°C. Creep experiments are performed at elevated temperatures with good fitting of Dorn creep and back-stress creep models. Activation energy measurements are made at 40°C, 80°C and 120°C. Wettability testing on copper substrates is used for surface tension, wetting force and contact angle measurements of SAC and SAC-La doped alloys at 250°C and 260°C.

In this work, scanning multiprobes microscopes were used to study the physical properties of biological, vitreous and ceramics samples. In particular, we have used three different scanning probe microscopy techniques to the study the samples. At first, an atomic force microscope was used to evaluate the mechanical properties of macrophages due to cell adhesion to an extracellular matrix and to study the changes in DNA molecules conformation treated with thymol and adsorbed onto a mica surface modified by poly-L-lysine. The results of these studies show that the cytoskeleton-mediated cell-matrix interactions directly affect biomechanical events in cells by modifying physical properties of the cytoskeleton and that the modification of mica surface using poly-L-Lysine provides a strong and firm bond with DNA. This strong fixation of DNA, allows the study of DNA conformational change on mica when interacting with tymol. The atomic force microscope was also used in studies of laser induced thermal expansion in commercial phosphate glasses. The ability of this technique to detect nanoscale surface deformations and the good agreement between theoretical and experimental results show the potential of this technique to study the amplitude and the dynamic of thermal effects in solid materials. In another study, conductive atomic force microscopy was used to analyze electrical properties of barium titanate semiconductor ceramic and their correlation with specific topographic features of the sample. Finally, using the scanning near-field optical microscopy, we studied interactions between cells and gold nanoparticles, without the need of fluorescent labeling on the nanoparticles, with high spatial resolution. During the presentation of these studies the challenges and necessary instrumentation for their realization was discussed. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, microscópios de varredura multi-sondas foram utilizados para o estudo de propriedades físicas de amostras biológicas, vítreas e cerâmicas. Em especial, usamos três diferentes técnicas de microscopia de varredura por sonda no estudo destas amostras. Primeiramente, um microscópio de força atômica foi usado para avaliar os efeitos na mecânica da membrana de macrófagos, verificando a interferência da adesão celular por uma matriz extracelular. Em seguida, estudamos as mudanças de conformação de moléculas de DNA tratadas com Timol e adsorvidas sobre uma superfície de uma mica modificada por poli-L-lisina. Os resultados destes estudos implicam que as interações célula-MEC mediada pelo citoesqueleto afetam diretamente os eventos biomecânicos das membranas, modificando as propriedades físicas do citoesqueleto celular, e que a modificação da superfície da mica utilizando poli-L-Lisina proporciona uma ligação forte e firme com o DNA. Esta forte fixação do DNA, permitiu o estudo da mudança conformacional do DNA na mica quando interagindo com o timol. O microscópio de força atômica também foi usado para realizar de estudos da expansão térmica em vidros fosfatos comerciais, induzida por um laser. A capacidade desta técnica de detectar deformações superficiais em nano-escala e a boa concordância dos resultados teóricos e experimentais mostra o potencial desta técnica para o estudo da amplitude e dinâmica de efeitos térmicos em materiais sólidos. Num outro estudo, a microscopia força atômica condutora foi usada para a análise de propriedades elétricas de cerâmicas de titanato de bário semicondutor e suas correlações com características topográficas específicas da amostra. Por fim, estudamos interações entre células e nanopartículas de ouro, com o uso da microscopia de varredura em campo próximo, sem a necessidade de marcação fluorescente nas nanopartículas e com alta resolução espacial. Durante a apresentação de cada um destes estudos foi discutido os desafios e parte da instrumentação necessárias para a realização dos mesmos.

Face à la finitude des ressources de la terre et de sa capacité d’absorption de la pollution, le développement d’écobétons pour un futur industrialisé durable représente un défi majeur de la science du béton moderne. En raison de sa nature hétérogène complexe, les propriétés macroscopiques du béton dépendent fortement des constituants de sa microstructure (ex. silicates de calcium hydratés [C–S–H], Portlandite, inclusions anhydres, porosité, agrégats, etc.). De plus, la nécessité d’une exploitation rapide et optimale des matériaux cimentaires émergents dans les applications industrielles demande de nos jours une meilleure compréhension de leurs particularités chimico-mécaniques à l’échelle micrométrique. Cette thèse vise à développer une méthode de pointe de couplage de la nanoindentation et de la spectroscopie quantitative aux rayons X à dispersion d'énergie (NI-QEDS), puis à fournir une caractérisation chimico-mécanique originale des phases microstructurales présentes dans les matrices réelles de ciments mélangés. La combinaison d’analyses NI-QEDS statistiques et déterministes a ainsi permis d’élargir la compréhension des systèmes avec ciment Portland et ajouts cimentaires (ACs) conventionnels ou alternatifs. Plus spécifiquement, l’étude des C–(A)–S–H (C–S–H incluant l’aluminium ou non) dans différents systèmes à base de ciments mélangés a montré des compositions différentes pour cet hydrate (variations dans les taux de Ca, Si, Al, S et Mg), mais ses propriétés mécaniques n’ont pas été significativement affectées par l’incorporation des ACs dans des dosages typiques. Les résultats présentés ont aussi démontré le rôle important des autres phases imbriquées dans la matrice de C–(A)–S–H, soit les inclusions anhydres dures (ex. le clinker et les ACs) et les autres hydrates tels que la Portlandite et les hydrates riches en aluminium (ex. les carboaluminates) avec des propriétés mécaniques plus élevées que celles des C–(A)–S–H. La thèse est basée sur cinq articles couvrant : (1) une analyse NI-EDS de systèmes incorporant des volumes élevés de pouzzolanes naturelles; (2) le développement de la méthode NI-QEDS; des analyses statistiques NI-QEDS (3) de systèmes avec cendres volantes et laitier, et (4) d’un système combinant ciment, calcaire et argile calcinée; et (5) une exploration déterministe NI-QEDS de systèmes conventionnels et alternatifs incorporant la poudre de verre, le métakaolin, le laitier ou la cendre volante. Finalement, en plus d’avancer les derniers modèles et méthodes micromécaniques, l’outil développé a fourni une perception chimico-mécanique originale des phases microstructurales et de leur arrangement. Le dévoilement de la signature chimico-mécanique de ces pâtes de ciments mélangés particulièrement complexes offre un savoir unique pour l’ingénierie des bétons de demain. / Abstract : Facing the limitedness of the earth’s resources and pollution absorption capacity, the development of eco-concrete for a sustainable industrialized future is one of the major challenges of modern concrete science. Due to its complex heterogeneous nature, the macro-scale properties of concrete strongly depend on the microstructure constituents (e.g., calcium-silicate-hydrates [C–S–H], Portlandite, anhydrous inclusions, porosity, aggregates, etc.). Moreover, the need for rapid and optimal exploitation of emerging binding materials in industrial applications urges today a better understanding of their chemo-mechanical features at the micrometer scale. This thesis aims at developing a state-of-the-art method coupling NanoIndentation and Quantitative Energy-Dispersive Spectroscopy (NI-QEDS), and providing an original chemo-mechanical characterization of the microstructure phases in highly heterogeneous matrices of real blended-cement pastes. The combination of statistical and deterministic NI-QEDS analysis approaches opened new research horizons in the understanding of Portland-cement systems incorporating conventional and alternative supplementary cementitious materials (SCMs). More specifically, the investigations of C–(A)–S–H (C–S–H including aluminum or not) in different blended-cement systems showed variable compositions for this hydrate (i.e., Ca, Si, Al, S and Mg contents), but the mechanical properties were not significantly affected by the incorporation of SCMs in typical dosages. The presented results also showed the important role of the other phases embedded in the C–(A)–S–H matrix, i.e., hard anhydrous inclusions (e.g., clinker and SCMs) and other hydrates such as Portlandite and Al-rich hydrates (e.g., carboaluminates) with mechanical properties higher than those of the C–(A)–S–H. The thesis is based on five articles focusing on: (1) the NI-EDS investigation of high-volume natural pozzolan systems; (2) the development of the NI-QEDS method; the statistical NI-QEDS analyses of (3) fly ash and slag blended-cement systems and of (4) a limestone-calcined-clay system; and (5) the deterministic NI-QEDS exploration of alternative and conventional systems incorporating glass powder, metakaolin, slag or fly ash. Finally, the developed tool not only advanced the latest micromechanical methods and models, but also provided original chemo-mechanical insights on the microstructure phases and their arrangement. Unveiling the chemo-mechanical signature of these highly-complex blended cement pastes further provided unique knowledge for engineering concretes for tomorrow.

The main goal of this study consists of the development of new asphalt mixes, based on industrial waste materials as replacement of natural aggregates. To achieve this purpose, a new characterisation of these pavements was proposed so to verify that the new mix has good mechanical performance without any detrimental impact to the environment.<p>This characterisation was divided in three distinct steps:<p>• a physical and chemical characterisation of the different constituents of asphalt concrete, as well the natural materials as the industrial waste considered as potentially secondary aggregates,<p>• a study of the bitumen-aggregate interface by means of two techniques: a qualitative method (scanning electron microscope) and a quantitative one (nanoindentation)<p>• an evaluation of the mechanical performance of mixes containing industrial waste, before and after recycling, by means of four standard road-engineering tests.<p>The numerous results allowed to put in evidence the possibility to reuse some industrial waste materials in asphalt concrete. In addition, this characterisation containing both chemical and mechanical aspects, at the microscopic and macroscopic scales, would permit the transposition of this study to the whole of asphalt concrete./<p>Le principal objectif de ce travail consiste en le développement de nouveaux mélanges bitumineux utilisant des déchets industriels en tant que remplacement des matériaux naturels. Pour ce faire, une nouvelle caractérisation de ces revêtements a été proposée afin de vérifier que le nouveau revêtement obtenu présente de bonnes performances mécaniques tout en évitant un impact environnemental néfaste.<p>Cette caractérisation a été scindée en trois étapes distinctes :<p>•\ / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

NiTiCu is a shape memory alloy that regains its original shape after large amount of shape changing deformation when heated above a critical temperature called reverse martensitic trans-formation temperature( Af). When external load is applied on the sample in twinned martensite phase at low temperature, it deforms by detwinning, accommodating large amount of strains. When it is heated above Af, the shape recovers by transformation of the martensite to austenite phase. However, the amount of shape recovery degrades over time due to internal factors such as precipitates, residual strains and thermal history as well as external factors such as stresses. Severe localized stresses induced by contacts result in plastic deformation that affect the reverse martensitic transformation and hence the shape recovery. In this work, we study how varying levels of contact stresses induced in NiTiCu thin film affect its shape recovery. NiTiCu thin films of six different compositions are deposited on Si(100) wafer by co-sputtering from elemental targets. After deposition, the films are annealed at 500 C for 4 h to make them crystalline. The composition of the films varied linearly with applied power to the targets. Uniformity in composition over a 4 inch substrate area is achieved by substrate rotation. All the films show ne grain microstructure after annealing. The subsurface of the Ni-rich films is columnar. Ni-rich films have annealing cracks and the crack width increases with Ni composition in the films. The roughness of as-deposited films is found to be more for Ni-rich films compared to Ti-rich films. The roughness of the Ni-rich and Ti-rich films increased after annealing. From the X-ray diffraction studies, it was observed that the films are nanocrystalline. Indentation is carried out using a Berkovich diamond indenter with spherical apex, at nine different locations with loads ranging from 0.25 mN to 25 mN. A predefined array is chosen for indentation such that the larger indents act as a guide to precisely locate minute indents generated at lower loads, with residual depth as small as 10 nm, for imaging in high-resolution microscopes like Scanning Electron Microscope as well as in Atomic Force Microscope . In Ti60 (a Ti-rich) lm, the residual indents generated at loads greater than 10 mN show radial cracks originating at corners. Average crack length increases with the maximum load used for generating the indent. Sequential sectioning of Ti48 (a Ni-rich) lm using Focused Ion Beam microscope, revealed that the cracks originate at the lm-substrate interface and reach the surface. In Ti48 lm, residual indents do not show any indentation cracks. The indentation stresses are accommodated by breaking of the columnar structure and the voids between them. Delamination of the film from the substrate is observed on either sides of the indent in both the Ti60 and Ti48 films. The hardness of the films is high at low loads and decrease as the load increases. The deformation by indentation at lower loads is mainly due to detwinning as only the apex of the indenter, which is nearly spherical, is in contact with the sample and the resulting stresses are low. As the load increases, the deformation starts getting accommodated through dislocations along with detwinning as the stress beneath the indenter increases. Spherical cavity model extended to SMA shows that inner hemisphere near the tip contains dislocations where stresses are very high, surrounded by detwinned region with stresses that are relatively low. When the sample is heated above reverse martensitic transformation temperature to induce shape recovery in the indents, only the detwinned region recovers to the original shape. Recovery ratio, quantification of shape recovery, is calculated from the depth of the indents before and after heating. Recovery ratio in Ti60 films is found to be large at low loads and decreases with increase in load. The decrease in shape recovery in Ti60 is attributed to the increase in the amount of plastic deformation at the expense of detwinning. Three-dimensional mapping of the surfaces shows that the recovery ratio is high at the apex of the indent at the maximum depth and reduces towards the edges of the indent. There is no evident recovery in Ti48 films. The shape recovery of SMAs can be achieved by Joule heating. When electric current is passed through the material, it heats up by Joule heating because of the intrinsic resistivity. The resistivity and hence the resistance would get effected by the dislocation based plastic deformation induced by the contact. This might result in shape recovery through resistive heating. Towards understanding this, the effect of contact stresses on electrical contact resistance is studied. Experimental setup is designed, developed and calibrated for studying the variation of electrical contact resistance of the NiTiCu thin films as a function of load. Electrical contact resistance is found to decrease with increase in applied load. Contact stresses in sub-micron NiTiCu thin films are simulated by carrying out nanoindentation at different loads. The recovery ratio is high when the stresses induced by the contact is less, at lower loads. The shape recovery ratio is reduced when the induced contact stresses in-creases. There is no shape recovery at the sharp edges of the indentation where contact stresses are very high. Hence, by carefully designing the features to reduce the stress concentrations, the performance of the device can be improved.