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A general X-ray multireflection method was applied to determine the stress level in deformed and recrystallised polycrystalline copper samples. Different reflections hkl were simultaneously used in the fitting procedure. The anisotropic diffraction elastic constants were calculated using the self consistent model and crystallographic texture. A significant decrease of the first order residual stresses was observed during recovery and recrystallisation. Diffraction peak widths and intensities were also examined for a few characteristic texture components during the recrystallisation process. Independently, synchrotron radiation and electron backscatter diffraction techniques were used to determine the stored energy in the examined material. The main result is that residual stress components start to reduce already before the recrystallisation process. The stored energy is strongly orientation dependent. It has the lowest value in the cubic texture component, which is dominating one in recrystalisation texture.

Bone is a composite material of collagen and porous hydroxyapatite crystallites, aligned parallel to each other, with the c -axis parallel to the long axis of the fibre. Its texture and crystallinity has been investigated by means of neutron diffraction, using the high intensity 2-axis diffractometer D20 at ILL in particular. We show spatially resolved pole figures on a composite sample of two bone pieces of different preferred orientation. We have selected the (1 1 1) reflection, which is nearly not affected by texture to characterise the crystallinity index, and (0 0 2) to show the texture because the c -axes of hydroxyapatite crystallites is directed along the axis of the bone.

Neutron diffraction was used to measure the lattice strains in Al/SiCp metal–matrix composite under an external load applied while the sample was in situ in the neutron beam. The evolution of the internal stresses and of the critical-resolved shear stress during bending were predicted by elastoplastic models. Calculations based on these models were verified by comparison with the results of the diffraction experiment. It was found that the self-consistent model correctly predicts the distribution of stresses between the two phases of the Al/SiCp composite. Finally, the parameters characterising elastoplastic deformation of the Al–matrix were determined.

The residual stress (RS) profile state of a palladium alloy sample, used in dentistry applications, has been determined by various diffraction techniques. An additional aim of this work was to improve different experimental methods dedicated to such RS evaluation, demonstrating that the X-ray, neutron and high-energy synchrotron X-ray diffraction (HESXRD) techniques are complementary when employed in different zones of the sample.

A general multi-reflection method was applied to determine the stress level in deformed and recrystallized polycrystalline copper samples. Different reflections hkl were simultaneously used in the fitting procedure. The anisotropic diffraction elastic constants were calculated using the self-consistent model and crystallographic texture. Important decrease of the first order residual stresses was observed during recovery and recrystallization. Independently, diffraction peak widths and intensities were examined for a few characteristic texture components during the recrystallization process. The importance of cubic orientation grains in the recrystallization process was confirmed.

We investigated the preferred orientation of hydroxyapatite Ca10(PO4)6(OH)2 (HAp) crystallites at the interface bone-implant in rabbit tibia bones, after 40 and 60 days of implantation. The implant had two faces, one coated and one non-coated with plasma-sprayed HAp (80 μm). We probed the samples with a spatial resolution of 0.5 mm starting from the interface to inspect the reorganisation of the HAp crystallite distribution and the crystallinity after implantation. For this texture study, we used the neutron 2 axis diffractometer D20 at the Institut Laue Langevin (ILL).

The neutron diffraction method was applied to determine the evolution of internal strains (and stresses) within an Al/SiCp metal matrix composite. The specimen was subjected to thermal treatment followed by different types of elastoplastic deformation. An Eshelby type model was used to study the contribution of different phenomena to the evolution of stress. The results of the experiment were compared with model predictions obtained using a self-consistent model of elastoplastic deformation. The validity of the use of this model for stress analysis was verified by comparison with a neutron diffraction measurement performed for an external load applied ‘in situ’. Hydrostatic phase stresses were experimentally found in the samples after thermal treatment. These stresses were modified due to plastic deformation, and significant relaxation of the microstresses was observed.

A new method for study the elastoplastic property of polycrystalline material is proposed. The neutron diffraction was used to measure the lattice strains in two-phase austenoferritic steel under external load applied in situ. The evolutions of the internal stresses and of the critical resolved shear stress during tensile uniaxial test were predicted by elastoplastic models. Calculations based on these models were compared with the results of mechanical tests and diffraction data. Finally, the parameters characterising elastoplastic deformation were determined for both phases of duplex steel.

During clinical use of hydroxyapatite-coated implants, mechanical stresses are added to pre-existing residual stresses. The magnitude of these stresses affects the coating's performance. In this work we studied, by neutron diffraction and conventional X-ray diffraction methods, the macrostresses induced by a plasma-spraying process in the coating and at the interface. Neutron diffraction is one of the most suitable techniques for studying the strain distribution in a bulk material. X-ray diffraction was used to determine residual stress in the hydroxyapatite coating. Using a neutron diffraction method at the nearest point to the interface, we saw no real difference between the stress observed on coated and that on non-coated samples. With the X-ray diffraction method, it appeared that the stress level was compressive on every sample. The major advantage of the neutron diffraction method is that measurements can be made on a thick coating in a nondestructive way. The disadvantage is the large-gauge volume that we had to use because of the relatively low intensity of the neutron beam. Polishing is necessary for measurements inside the material when using the X-ray method. This destructive method may alter the stress field of the deposit.

The method of the neutron diffraction has been widely applied to determine the residual stresses in composite materials. In this work,the neutron diffraction technique is used to determine the stresses in 7075 aluminum alloy reinforced with 27% volume fraction SiC whiskers that was treated by the coldrolling technique. The strains in Al matrix and in SiC phase have been converted to stresses by applying a stress separation technique. The elastic and the thermal or plastic mismatch stresses due to cold-rolling treatment and manufacture in the Al matrix and in the SiC phase are estimated. The stresses in the Al matrix and in the SiC phase of the first order are different from the stresses of the second order. The stress values of the thermal or plastic are tensile in Al matrix and compressive in SiC reinforcement.

The present study is dedicated to the evaluation of residual stresses at surfaces, in the bulk of materials and at interfaces, by classical X-ray and neutron diffraction and high-energy synchrotron measurements. It is mainly focused on the improvement of these experimental techniques. The new developed methods have been applied to a coating that consists of leucite moulded on a Palladium alloy substrate. These materials are employed in dental applications.

The stress field existing within a polycrystalline material can be described at different scales of interest. Here, the stresses for two different scales are considered: the macro stress which is defined as the average stress over the sample volume containing a large number of polycrystalline grains, i.e. over many millimeters or even centimeters; and the second order stress which is defined as the deviation of the stress for a particular grain from the macroscopic value. The second order stresses vary on the scale of the grain size, or the inter-particle spacing in composite material. In this work the second order stress was predicted using the self-consistent model of elasto-plastic deformation for Al/SiCp composite. The results were verified using neutron diffraction method of stress measurement.

To standardize industrial implant production and make comparisons between different experimental results, we have to be able to quantify the crystallinity of hydroxyapatite. Methods of measuring crystallinity ratio were developed for various HA samples before and after plasma spraying. The first series of methods uses X-ray diffraction. The advantage of these methods is that X-ray diffraction equipment is used widely in science and industry. In the second series, a neutron diffraction method is developed and the results recorded are similar to those obtained by the n modified X-ray diffraction methods. The advantage of neutron diffraction is the ability to obtain measurements deep inside a component. It is a nondestructive method, owing to e the very low absorption of neutrons in most materials.

As part of a characterization research on hydroxyapatite (HAp) plasma deposits for hip prosthesis, crystallinity and residual stresses weredetemiined at the interface Hap'TA6V. A traditional method employed by several laboratories is based on X-ray diffraction by a powder mixture of the investigated HAp sample with a standard of crystallinity Al2O3 Four new methods were investigated for determining the crystallinity of HAp sample, two of which are based on x-ray diffraction, one on neutron diffraction and one on the infrared absorption spectrometry. Whereas the three techniques require the use of powders, the neutron technique can be applied also to the intact HAp deposits. All four methods provide reasonable results, not very different one from each other, with a greater accuracy than for the x-ray and IR methods.

We present an original method for the determination of residual stresses in plastically deformed polycrystalline material (1, 2). The advantage of our method is that the anisotropy of residual stress field can be determined. Moreover, the principles of the diffraction experiment for internal stress measurement are recalled. Using the neutron and X-ray techniques, we have determined the first and the second order stresses for cold rolled steel.

In some metallic materials the dominating recrystallization mechanism can be described by the oriented growth behaviour. Phenomenological laws state that in selected materials only these nuclei grow intensively which have a given misorientation relation with the deformed matrix. This description is frequently verified in f.c.c. metals and generally reported misorientations correspond approximately to 400 rotation around the axis. Basing on the above ideas the recrystallization model, including the compromise condition, was formulated and applied to the study of recrystallization textures of rolled polycrystalline aluminium.

Neutron diffraction was successfully applied to measure the lattice strain distribution in polycrystalline materials. The experimental data were studied with help of self-consistent model. Using a non-standard method of analysis the values of macro and microstresses in textured ferritic steel were estimated. The validity of self-consistent model for prediction of mismatch stresses in two phase materials was examined. The theoretical results were successfully compared with the diffraction data for “in situ” tensile test. The parameters characterising elastoplastic deformation of polycrystalline grain were determined.

The aim of this work is to improve some experimental techniques dedicated to the evaluation of residual stress (RS). These methods have been applied to a sample consisting of a glassy ceramic coating moulded on a metallic substrate (palladium-silver alloy) used in dental applications. Knowing the residual stress distributions is very important to determine the lifetime of the sample.

This study deals with skin-friction drag analysis in underwater swimming. Although lower than profile drag, skin-friction drag remains significant and is the second and only other contribution to total drag in the case of underwater swimming. The question arises whether varying the thermal gradient between the underwater swimmer and the pool water may modify the surface shear stress distribution and the resulting skin-friction drag acting on a swimmer's body. As far as the authors are aware, such a question has not previously been addressed. Therefore, the purpose of this study was to quantify the effect of this thermal gradient by using the integral formalism applied to the forced convection theory. From a simplified model in a range of pool temperatures (20-30 degrees C) it was demonstrated that, whatever the swimming speeds, a 5.3% reduction in the skin-friction drag would occur with increasing average boundary-layer temperature provided that the flow remained laminar. However, as the majority of the flow is actually turbulent, a turbulent flow analysis leads to the major conclusion that friction drag is a function of underwater speed, leading to a possible 1.5% reduction for fast swimming speeds above 1m/s. Furthermore, simple correlations between the surface shear stress and resulting skin-friction drag are derived in terms of the boundary-layer temperature, which may be readily used in underwater swimming situations.

Among the different techniques, neutron scattering is the only one which can investigate directly inside the metal-adhesive interface because the linear absorption coefficients are much lower than those observed with the X-Rays. The specimen was assembled by a single component epoxy adhesive. The quality of the bonded joint was controlled by neutron radiography. The assembly was subjected to a macroscopic strain by means of a special set-up. The measurement of stresses near the interface made under different experimental conditions. The results obtained are compared with those from finite element calculations.

The use of the implants has become current since 1930. With the improvement of technology, metals have been used in the medical field. As a long-term establishment is a meter of the therapeutic success, it is necessary to use biocompatible implants in order to have good mechanical and fracture resistance. In orthopaedic surgery Titanium (Ti-Al-4V) implants are currently coated with hydroxyapatite (HAp), Ca10 (PO4)6 (OH)2, in order to obtain a stable and functional direct connection between the bone and the implant. At the implant-bone interface the new bone reconstituted after implantation must have the same orientation as the natural bone in order to accept the implant. Therefore we studied the texture of the new bone crystals reconstituted at the interface applying non destructive x-ray diffraction. The required high spatial resolution was achieved utilizing high-energy synchrotron radiation on ID15 at ESRF in Grenoble, France.

A grade 6 cobalt-based superalloy was coated on steel substrate by the Plasma Transferred Arc (PTA) method. The macrostructure and microstructure of the interface and of the co-based superalloy layers are studied. The superalloy grains are deformed during the cladding process. At the interface, the superalloy grains elongate and tend to follow the geometry of the interface. Observation with a scanning microscope reveals zones of localised Affected Zone Thermal at the interface. A numerical analysis has been carried out to simulate the PTA process deposition with physical conditions and mechanical properties using the Abaqus code. A simplified model based on energy conservation and wall functions is used to predict the process, solid shield and shroud on the temperature and the residual stress of the PTA technology at the surface of coating layer and the interface. The results reveal that the residual stress obtained by the numerical simulation are in very good agreement with experimental results performed by the neutron diffraction.

The aim of this work is to improve some experimental techniques dedicated to the evaluation of residual stress at the surface and in the bulk of materials, by means of high-energy synchrotron measurements. This method has been applied to a metallic substrate used in dental applications.

The X-ray diffraction method has been applied to determine the internal stresses in two phases austeno-ferritic steel during uniaxial tensile test. The elasto-plastic deformation model was used to predict internal stresses and critical resolved shear stress for the both phases. The model calculations were successfully compared with the information obtained from the shift and broadening of diffraction peak. Finally, the parameters characterising elasto-plastic deformation for duplex steel were determined.

Deformation by rolling induces in general a strong crystallographic texture, hence an important material anisotropy. This is a reason why the cross-rolling is sometimes applied in order to symmetrize the crystallographic texture. Such an operation modifies also residual stresses. The goal of this study was to characterize residual stress and texture changes during simple and crossrolling in polycrystalline copper and ferritic steel. The obtained results show that important modification of the first order residual stresses occurs during cross-rolling, while the level of the second order ones is approximately constant. Experimental results were analysed using an elastoplastic deformation model.

The utility of dental porcelain, as a restorative, can be extended in the PFM technique, as a strengthening mechanism for porcelain. Several layers of dental porcelain are fused to a metal casting. The coefficient of thermal expansion of these porcelains must be suitably matched with that of the alloy and the melting range of the alloy must be raised sufficiently above the fusion temperature of the porcelain for a successful operation.This study deals with the evaluation of the mechanical behaviour at the interface of a glassy-ceramic coated onto palladium alloy substrate. Microstructural characterisations and residual stresses evaluations are carried out in the different layers of the sample. Residual stress measurements have been realised by neutron diffraction and high-energy synchrotron radiation to characterise the mechanical state of the sample.The mechanical properties of metallic layers greatly depend on the residual stresses induced by the manufacturing of the coating. It is therefore very important to characterise these stresses. Some general aspects of the evaluation of residual stress are reported. A micro-mechanical model used in the study and a quick theoretical calculus are also presented.Diffraction measurements have been performed in different zones in the sample, in particular, neutron diffraction to analyse both the glassy ceramic surface and the bulk of the leucite and of the palladium alloy; high energy synchrotron radiation for the metal/ceramic interfaces. In this way, they have allowed to obtain the best information in different regions of the analysed sample. For these experimental techniques, measurements carried out at the interface between two different materials are difficult to analyse due to great parasitic peak shifts which are obtained in such condition.Therefore, it is important to correct the parasitic peak shifts which appear in these cases and which are not linked to the stress state of the scanned volume. This effect can be much greater than the peak shifts induced by the stresses. To solve this problem a complete modelling of 2-axis spectrometers, based on Monte Carlo calculations, has been developed either for neutrons or for synchrotron radiation. It allows also to optimise the experimental conditions and to define precisely the true volume of the neutron gauge.The microstructure of a leucite dental glass-ceramic and of the palladium alloy substrate were finally investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The Transmission Electron Microscope technique (TEM) was also employed to study the structural properties of both materials.; L'importance des porcelaines dentaires (pour les méthodes de reconstruction) est liée à l'utilisation de la technique de la Porcelaine Fondue sur Métal (PFM) pour améliorer la résistance des dépôts de céramique.Plusieurs couches de porcelaine sont déposées sur un métal élaboré par moulage. Le coefficient de dilatation thermique de ces porcelaines doit être le plus proche possible de celui de l'alliage. La température de fusion de l ‘alliage doit, de plus, être supérieure à celle de la céramique pour réussir l'opération.Cette étude porte sur l'évaluation du comportement mécanique à l'interface d'une céramique déposée sur un substrat d'alliage de palladium. Une caractérisation microstructurale et l'évaluation des contraintes résiduelles ont été menées sur différentes couches de l'échantillon. Des évaluations de contraintes ont été réalisées par diffraction neutronique et par rayonnement synchrotron à haute énergie pour caractériser l'état mécanique de l'échantillon. En effet, les propriétés mécaniques des couches métalliques dépendent grandement des contraintes résiduelles induites par l'application du revêtement. Il est alors essentiel de caractériser ces contraintes. Nous présentons ici les aspects généraux de l'évaluation des contraintes résiduelles, un modèle micro-mécanique appliqué dans notre étude et un bref calcul théorique.Des mesures par diffraction ont été réalisées dans différentes zones de l'échantillon. En particulier, nous avons employé la diffraction neutronique pour analyser la surface et l'épaisseur de la céramique vitreuse et lecoeur du substrat métallique, et le rayonnement synchrotron à haute énergie pour étudier l'interface céramique - métal. De cette façon, nous avons obtenu les meilleures informations sur les différentes régions de l'échantillon analysé.Pour ces techniques expérimentales, les mesures conduites aux interfaces entre deux différents matériaux sont très difficiles à analyser à cause des déplacements parasites importants du pic de diffraction qui existent dans ces conditions. Ces déplacements ne sont pas liés à l'état de contraintes du volume balayé et peuvent être plus importants que les effets induits par les contraintes. Nous avons développé, pour résoudre ce problème, une modélisation complète des spectromètres 2-axes, basée sur une simulation de type Monte Carlo. Cette modélisation est effectuée à la fois pour les spectromètres de neutrons, et pour les installations utilisant le rayonnement de synchrotron. Elle permet d'optimiser les conditions expérimentales et de définir précisément la taille et la position du volume sonde.La microstructure de la céramique dentaire et de l'alliage de palladium a été enfin étudiée en utilisant la diffraction des rayons X (DXR), la Microscopie Electronique à Balayage (MEB) et la Spectrométrie à Dispersion d'Energie (EDS). La Microscopie Electronique à Transmission (TEM) à été aussi employée pour étudier les propriétés structurales des matériaux.