Diffusion-controlled liquid bismuth induced intergranular embrittlement of copper

The consequences of the contact between liquid bismuth and a copper bicrystal are investigated at 500°C. Atoms of bismuth are shown to penetrate and embritlle the copper grain boundary. Grain boundary concentration profiles of bismuth are obtained on fracture surfaces by both Auger electron spectroscopy and He4+ Rutherford backscattering spectroscopy. The maximum bismuth intergranular concentration is calculated from experimental data to be about 1.7 monolayers (near the liquid bismuth / solid copper interface). The overall profiles are significantly different from typical erfc profiles and an interpretation is proposed, based on the coupling effect between grain boundary diffusion and non-linear segregation. These results allow us to conclude on the absence of grain boundary wetting for the Cu / Bi system at 500°C

Citizenship, property, and place: Land and housing in South Africa. - Page 173

Cette étude constitue, une approche théorique globale des phénomènes d'instabilité morphologique susceptibles d'affecter une interface mobile. Elle comprend : a

Corrosion of austenitic stainless steels in hot concentrated aqueous Na OH solutions.

International audienc

Aspects électrochimiques et cristallographiques de la corrosion des aciers inoxydables austénitiques dans les solutions de soude concentrées et chaudes.

National audienc

On the Forward Scattering by Targets below a Multilayer

A method for solving forward scattering problems in through-the-wall applications with multilayered walls is presented. Targets are perfectly conducting cylindrical scatterers, with circular cross section, hidden by the wall. The technique is developed in the frequency domain, and it employs expansions of the scattered fields by the targets through cylindrical waves as basis functions. Numerical results allow to solve the scattering problem in large domains, with a semi-analytical technique

Experimental atmospheric ageing of archaeological artefacts and contemporary low-alloy steel in climatic chamber

Conférence du 5 au 9 Septembre 2005. Communication par affiche

New methodological approach to morphological kinetics

The way of characterizing an interfacial morphology and its relation to the mechanism of transformation of a solid are discussed in this paper for the particular case of electrochemical dissolution. Several parameters, useful in the description of the morphology and its variation with time, are proposed. Moreover, a physical model and its mathematical formulation are developed in order to predict the morphological changes of the interface. The results of numerical and analytical solutions to this problem are compared with experimental data obtained for two cases: aqueous corrosion of copper and electrolytic polishing of a stainless steel

Steel corrosion in concrete: Determinist modeling of cathodic reaction as a function of water saturation degree

International audienceThe prediction of the long-term behavior of reinforced concrete structures involved in the nuclear waste storage requires the assessment and the modeling of the corrosion processes of steel reinforcement. This paper deals with the modeling of the cathodic reaction that is one of the main mechanisms of steel rebar corrosion. This model takes into account oxygen reduction and oxygen diffusion through a diffusion barrier (iron oxide and/or carbonated concrete) as a function of water saturation degree. It is demonstrated that corrosion rate of reinforcement embedded in concrete with water saturation degree as low as 0.9 could be under oxygen diffusion control. Thus, transport properties of concrete (aqueous and gaseous phase, dissolved species) are key parameters that must be taken into account to model electrochemical processes on the reinforcement

Ability of acoustic emission technique for detection and monitoring of crevice corrosion on 304L austenitic stainless steel

International audienceThis experimental work was aimed at investigating the ability of acoustic emission (AE) technique for detection and monitoring of crevice corrosion on 304L austenitic stainless steel. Crevice initiation, propagation and repassivation was controlled by additions of hydrogen peroxide and hydrochloric acid and by the extent of the applied torque of crevice assembly, in the presence of chloride ions. The simultaneous measurements of corrosion potential of the specimen and AE global activity during the test, as well as the characterization of acoustic parameters of AE signals, evidences a good correlation between potential and AE activity fluctuations, AE rate and amplitude of crevice damage in terms of weight loss and metallic surface affected, in each tested experimental condition. Moreover, the evolution of cumulative% of AE signals number versus selected acoustic parameters shows that rise time, counts number, duration and cumulative energy of AE signals are affected by crevice development. Finally, visualization of crevice initiation and propagation during the test allows to propose that bubbles formation from cathodic reactions within the crevice is the emissive mechanism