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

Progress Report on Target Development

The present document is the D08 deliverable report of work package 1 (Target Development) from the MEGAPIE TEST project of the 5th European Framework Program. Deliverable D08 is the progress report on the activities performed within WP 1. The due date of this deliverable was the 5th month after the start of the EU project. This coincided with a technical status meeting of the MEGAPIE Initiative, that was held in March 2002 in Bologna (Italy). The content of the present document reflects the status of the MEGAPIE target development at that stage. It gives an overview of the Target Design, the related Design Support activities and the progress of the work done for the safety assessment and licensing of the target

Pressions de sublimation de N

Des mesures précises de la pression de sublimation de N2O ont été effectuées entre 125 K et 147 K. Jusqu’à présent il n’existait pas de valeurs fiables de cette grandeur au-dessous de 146 K. De nos résultats et de mesures antérieures de chaleurs spécifiques de N2O solide nous déduisons son entropie et son enthalpie à O K : s0 = 1,43 cal mol–1 K–1, h0 = – 5 799 cal mol–1. Ces grandeurs permettent de calculer, à l’aide des capacités calorifiques, les pressions de sublimation à basse température avec une meilleure précision que les mesures expérimentales

Determination of the diffusion coefficients of iron and chromium in pb17li

International audienceA method with controlled forced convection using a cylindrical rotating sample has been devised to determine the diffusion coefficients of iron and chromium dissolved in Pbl7Li liquid metal at 500°C. The following values have been obtained: D(Fe/Pb17Li)500°C = 4±2 × 10−14 m2 s−1 fD(Cr/Pb17Li)500°C = 8±2.5 × 10−11 m2 s−1. A value of chromium solubility in Pb17Li at 500°C has also been deduced, Cs = 90.9 g m−3 (10 wppm), which is compatible with the existing data at lower temperatures

Corrosion of metallic materials in flowing liquid lead-bismuth

Corrosion tests of martensitic and austenitic steels were performed in a forced liquid eutectic Ph-Bi circulation loop. Experiments were carried out at 470°C and 600°C. Two oxygen concentrations in Pb-Bi were studied: $10^{-6}$ wt% and $10^{-7}-10^{-8}$ wt%. The results showed that at 470°C, all the tested steels have a satisfying corrosion behaviour for both oxygen contents. An oxide layer is formed on martensitic steels (T91 and EM10); its thickness depends on the oxygen content. It is constituted of an outer layer of magnetite and an inner (Fe, Cr)$_3$O$_4$ spinel layer. Austenitic steel 316L is protected by a very thin oxide layer ($<$ 1 $\mu$m). At 600°C, martensitic steels (T91 and EM10) undergo an important oxidation for both oxygen contents (after 1000h, the thickness of the oxide layer varies from 10-15 $\mu$m to 20-25 $\mu$m depending on the oxygen content). The oxide layer is constituted of (Fe, Cr)$_3$O$_4$ spinel and appears porous. Austenitic 316L undergoes severe dissolution at the lowest oxygen content in Ph-Bi and partial dissolution and oxidation at the highest oxygen concentration. Erosion phenomena were observed on all the steels

Corrosion behaviour of a high strength nickel base alloy in Gas Cooled Reactors (GCR)

International audienceNi-Cr-W alloys are claimed to present high creep strength, a good hot workability together with improved oxidation resistance. Recently developed Haynes 230 could be a promising candidate material for the high temperature structures in Gas Cooled Reactors (GCR). However, corrosion resistance of Haynes 230 is unknown in the reactor specific environment namely impure He up to 850-950DC. Generally speaking the impurities in the cooling helium react with most Cr-containing alloys. They can produce surface scale formation, bulk carburisation and-or decarburization, depending on the gas chemistry, the alloy composition and the temperature. The changes in the bulk carbon content and the associated structural transformations can notably degrade the material mechanical properties and must definitely be precluded. Corrosion properties of Haynes 230 were investigated in a purposely-designed facility under different helium media at about 950DC. Short and longer experiments were carried out in simulated GCR coolant in order to assess the corrosion variability to test conditions. More specifically, the oxide scale formation and a deleterious reaction destructing the protective oxide layer were studied. Main factors impacting on this previous reaction, such as the carbon monoxide partial pressure in the gas atmosphere and the activity of the reactive elements in the alloy were investigated. The reaction mechanism is discussed in the light of published models