In situ XRD analysis of the oxide layers formed by oxidation at 743 K on Zircaloy 4 and Zr–1NbO

Abstract Two alloys, having different oxidation behaviour (Zy4 and Zr–1NbO), have been investigated during oxidation at high temperature (743 K) and low oxygen pressure (10 kPa) by in situ X-ray diffraction (XRD). Tetragonal phase content and ‘pseudo-stresses’ on the monoclinic phase have been measured as a function of the oxide layer thickness. The tetragonal phase contents are similar for both alloys and decreased with the oxide layer thickness. Pseudo-stresses were much more compressive on Zr–1NbO alloy, with limited changes at the corrosion kinetics transition. On cooling, the tetragonal fractions do not change, while ‘pseudo-stresses’ decreased in different ways for the two alloys. Wit…

Investigation of MAFAPAS processing parameters for producing dense nanostructured FeAl

Understanding and Predicting Plutonium Alloys Aging: A Coupled Experimental and Theoretical Approach

Understanding plutonium aging is a real challenge that requires developing very ambitious modeling and experiments. Examples of the different techniques developed and the physical values that can be reached are presented here.

Spatiotemporal dynamics in the oxidation of groups IV?V metals: study of zirconium

Abstract This paper focus on the mechanism of zirconium oxidation at 850 °C by X-ray diffraction (XRD) and the interactions between chemical (oxide growth, phase proportion) and physical processes (oxide scale texture, mechanical stresses). The structural gradients in the oxide scale composed of monoclinic ZrO 2 (higher proportion) and tetragonal ZrO 2 were revealed by XRD at variable incidence. The spatial evolution of the monoclinic zirconia texture through the oxide scale was shown and quantified. Relaxation of the oxide compressive stresses was observed for different oxidation times and correlated to kinetic breakaway evidenced by other methods. A structural mechanism of the oxide forma…

Investigation of mechanically activated field-activated pressure-assisted synthesis processing parameters for producing dense nanostructured FeAl

The parameters of the mechanically activated field-activated pressure-assisted synthesis (MAFAPAS) process, which were recently developed and patented for producing dense nanostructured materials, were studied in the case of the B2-FeAl intermetallic. Based on x-ray diffraction (XRD) experiments, residual stresses XRD analysis, relative density measurement, and secondary-electron microscopic observations, the optimal synthesis conditions (time, current intensity, and pressure) were studied. Fe + Al powders were comilled in a specially designed planetary mill to obtain a mixture of reactants at the nanoscale without the formation of any product. The milled mixtures were then subjected to a h…

Determination of single crystal elastic constants in textured polycrystalline materials: inverse approach coupling x-ray diffraction and self consistent model applied to a copper sample

La diffraction des rayons X couplee a l'utilisation d'un modele polycristallin (modele auto-coherent) est utilisee pour determiner les constantes d'elasticite monocristallines d'un materiau polycristallin texture. En effet, la connaissance du tenseur de rigidite elastique cijkl d'un solide est fondamentale pour les etudes s'attachant a la comprehension des proprietes mecaniques de la matiere (approches theoriques ou experimentales). Si, d'autres techniques permettent de determiner le tenseur d'elasticite d'un materiau (ultrasons par exemple), elles necessitent souvent l'utilisation d'un monocristal. Ceci n'est pas toujours realisable, en particulier pour des alliages de concentrations varia…