In the present paper, a synthesis of the relations between diffraction stress analysis and multiscale modelling is presented. It is found that, although models give good qualitative and quantitative results in the elastic field, the extension to internal stresses of elastic-plastic origin remains semi-quantitative and many studies are still required to obtain a consistent formulation between diffraction and modelling.

The determination of residual stresses and the analysis of phases in zirconia layers obtained after oxidation of Zy-4 and Zr-1%Nb-O sheets have been performed using X-ray diffraction with synchrotron radiation at 20 and 400°C. These experimental analyses have been compared with calculations using a micromechanical approach (thermoelastic behaviour) and also with a macroscopic approximation of the thermal stress due to cooling. The main result is the small influence of cooling on the residual stresses developing in the zirconia layer, especially for Zr-1%Nb-O.

A self-consistent elastic-plastic model has been developed for the analysis of the behaviour of rolled samples of zirconium 702 during mechanical loading. The thermal residual stresses produced by cooling from the annealing temperature to room temperature have been determined and compared to X-ray diffraction results. The elastoplastic behaviour of zirconium in tensile tests along the rolling and transverse directions has been simulated and compared to the experimental results. The influence of texture and of existing thermal stresses on the response of the material could be studied and explained by this approach.

In this study, we present an analysis of the internal stresses generated during cooling of alumina-chromium composites using a micromechanical approach by a finite element method. Residual stress fields are calculated for microstructural models derived from a scanning electron microscope image. Results show in particular that particles with concave shapes can generate relatively high local plastic deformation and residual stress distributions in the adjacent matrix that are very different from those of particles with a spherical shape. We present also the experimental determination of residual stresses using synchrotron radiation from LURE. We show that measurements are possible and the results concerning the mean stresses in the alumina and chromium phases are analyzed.

Homogeneity methods are very helpful in the interpretation of X-ray line shift and broadening. The use of self-consistent models becomes general, but the information given by these models, which is shown to be strongly linked with diffraction measurements, can not yet be completely exploited. It is in particular shown that the intra-phase heterogeneity of strains should in certain cases be reflected by the line broadening behaviour.

A phenomenological relation is proposed for the description of the mechanical behaviour of Zr 702α polycrystalline samples deformed in channel die compression at room temperature. The identification of the parameters of the model from macroscopic stress-strain curves shows a good description of the anisotropy of the material. The analysis of the identified parameters shows the role of the activated deformation modes in the different samples.

In multiphase materials, X-Ray Elasticity Constants (XEC) depend on the nature and volume fraction of each phase constituting the polycrystal. These XEC play a leading role during X-Ray diffraction stress analysis. Self-consistent scale transition models have been developed in order to simulate the XEC characteristics of several two-phase alloys. This work makes possible the quantitative study of the influence of the second phase on the results of X-Ray stress analysis.

The impregnation of a fibrous preform by a liquid metal is one of the techniques used to prepare metal matrix composites (MMC). The preparation by impregnation may however lead to defects like microporosity. The micropores present in MMC result from the superposition of two processes: the trapping of gas by capillarity during the infiltration phase and the formation of additional porosity related to solidification shrinkage. These two processes are analyzed in this paper and physical models are proposed for their description. It is then shown how the formation of microporosities can be simulated numerically using these models. Finally, prospects for a better numerical simulation of the preparation of MMC by impregnation are discussed.

This study concerns the influence of certain metallurgical factors, like the addition of a mixture of rare earth metals (mischmetal) and of overheating, on the microstructure and the tensile properties of alloy A319-2 (Al-Si-Cu with 0.4, 0.8 and 1.2% iron) The new phase linked with mischmetal has a needle - and/or platelet - shape as the β-iron phase and impedes the flow of the liquid metal during casting, thus creating porosity. The different types of particles present in the microstructure remain after the T6 thermal treatment. In the alloys containing 1.2% iron, the length of the β phase and mischmetal particles is slightly smaller than in the alloys with 0.4% Fe or 0.8% Fe, after the addition of 5% mischmetal and overheating at 950°C. This explains the better tensile elongation of the 1.2%Fe-5% mischmetal alloy cast at 950°C instead of 750°C. UTS and yield strength are decreased by the addition of mischmetal but are slightly improved by overheating. Overheating at 950°C decreases the yield strength only in the 1.2% Fe-0% mischmetal alloy.

The multiplication of magnetic domain walls under the effect of induced currents developed during high frequency magnetization loops is experimentally investigated in ultra-soft nanocristalline alloys in order to determine the effective anisotropy and to check the predictions of the Random Anisotropy Model used to explain their extreme softness. For the first time, direct observation of multiplication is achieved and resulting effective anisotropy determinations underline the importance of induced anisotropy upon effective anisotropy.

The corrosion resistance of two aluminium alloys, 6063 and 3003, has been compared using a 0.5 M sodium chloride solution. The results obtained with electrochemical and metallographic techniques show that alloy 6063 is more resistant than alloy 3003 at 25°C. The corrosion rate tends to increase as the pH deviates from neutrality. When the chloride concentration is decreased, the resistance to pitting corrosion is improved for both alloys. The influence of the temperature of the medium on the behaviour of the two alloys has also been studied. In the case of alloy 3003, the corrosion rate (Icor) increases with temperature up to 55°C, but drops back to its room temperature value at 65°C. In the case of alloy 6063, Icor decreases as temperature is raised up to 65°C. At all testing temperatures, the 6063 alloy has a better corrosion resistance than the 3003 alloy.