Search results for "eutectic"
showing 10 items of 67 documents
Development of a liquid Pb-Bi target for high-power ISOL facilities
2016
Abstract This paper describes some R&D activities conducted in support of the design and safe operation of a high-power liquid Pb-Bi target within the LIEBE (Liquid Eutectic Lead Bismuth Loop Target for EURISOL) project. The target material is lead bismuth eutectic (LBE) which also acts as a primary coolant. As a consequence of interaction of the highly pulsed 1.4-GeV protons at ISOLDE with the target, heat powers of the order of 2 GW would be instantaneously deposited in the target during a bunch. Considerable R&D effort is thus required to demonstrate its continued coolability and structural integrity. This paper mainly reports on the conjugate flow (CFD) and heat deposition (Monte Carlo)…
Lead–gold eutectic: An alternative liquid target material candidate for high power spallation neutron sources
2011
Abstract One of the main technical concerns of Megawatt-class spallation neutron sources is the removal of the heat deposited in the target station. A way to overcome it is to use targets consisting of flowing liquid metals, but the already tested materials – mercury and lead–bismuth eutectic (LBE) – are not unproblematic. We show here that another eutectic alloy containing lead and gold (LGE) could be a suitable alternative. Besides a chemical toxicity lower than mercury, this low melting-point alloy has the advantage of being solid at RT. Moreover, it combines a neutron production similar to mercury and LBE with smaller amounts of alpha-emitting nuclides, relieving safety and environmenta…
Magnetic field effect on the corrosion processes at the Eurofer–Pb–17Li flow interface
2015
Abstract Structural and elemental analyses of the RAFM steel (EUROFER 97) interface with flowing Pb–17Li eutectic (velocity 5 cm/s at 550 °C, 1000 h) under the action of a strong magnetic field (B = 1.7 T) were performed using optical microscopy, SEM, confocal microscopy, precision micro-hardness methods, SIMS and point or line-scan EDX analyses. The results show that the magnetic field induces a faster crushing of martensite into the grains, a deeper dissolution of grain boundaries, an enhancement of the Fe and Cr mass transfer and a fast detachment of corrosion layers due to MHD effects.
Preliminary corrosion studies of P-91 in flowing lead–lithium with and without magnetic field for Indian lead–lithium ceramic breeder test blanket mo…
2014
To study the corrosion of P-91 (9% chromium and 1% molybdenum) material with lead–lithium (Pb–Li) eutectic, two experiments were carried out in a forced convection loop, at eutectic temperature of 550 °C. The first experiment was carried out at a velocity of 15 cm s−1 for 1000 h and the second experiment, at a velocity of 30 cm s−1 for 2700 h. In both the experiments, P-91 sample coupons were exposed to Pb–Li flow in the presence and absence of magnetic field. Samples were analyzed using an optical microscope, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Micro-Vickers hardness testing was also carried out. Dissolution of elements into liquid metal is the main…
Iodocyclization of 2-Methylthiophenylacetylenes to 3-Iodobenzothiophenes and their coupling Reactions under More Sustainable Conditions
2022
We report the first example of iodocyclization of readily available 2-methylthiophenylacetylenes in a deep eutectic solvent (ChCl/urea 1/2, mol/mol) as recyclable and more sustainable solvent with respect to the classical VOCs employed so far. The process successfully afforded a variety of 3-iodobenzothiophenes in good to high yields starting from differently substituted substrates, with the possibility to recycle the DES several times without appreciable lowering of the product yield. The 3-iodothiophenes thus synthesized are known to be important precursors of biologically active molecules and functionalized heterocycles, and were successfully employed for performing representative Sonoga…
Hydrogen Formation on Phase Boundaries of Sn/Al
2002
The present paper continues our earlier study of the embrittlement of Sn-Al eutectic alloy in water vapor and hydrogen emission from it, Atomically clean interfaces of solid phase joints of Sn with Al served as simple phase boundary models for this system. It was found by SIMS, X-ray and SEM techniques that the brittleness is caused by chemical adsorption of hydrogen on phase boundaries. This process is facilitated by structural defects. The reaction of hydrogen with phase boundary occurs first in regions of micro-and submicrocracks. The effect is irreversible one and it is associated with the formation of SnH4 that is instable and decomposes at the room temperature. The phase boundary of S…
Phase behaviour of binary mixtures of colloidal charged spheres
2008
Abstract As a step towards the modelling of binary metal alloys we here report on the shape of the phase boundary of two deionized charged sphere colloidal suspensions as a function of mixing ratio and particle density. Their size ratios are r = 0.68 and r = 0.56. Both aqueous suspensions of polystyrene copolymer spheres crystallize in a body-centred cubic structure. Interesting differences in the shape of the phase boundary are observed. In the first case a peaked increase of crystal stability was observed for a mixing ratio of p = 0.2–0.3, which gives the fraction of small spheres. Also in the second case the stability of the crystalline phase is larger than expected for an ideal solid so…
The Role of Diffusion Accommodation and Phase Boundary Wetting in the Deformation Behaviour of Ultrafine Grained Sn-Pb Eutectic
2010
Mechanical properties, microstructure of the Sn–38wt. %Pb eutectic and the development of deformation - induced diffusion processes on interphase boundaries (IB) were investigated. Experiments were carried out both in deformed and annealed states of eutectic using micro- and nanoindentation, SEM, AFM and optical microscopy techniques. It was found that the deformation of the annealed alloy is localized at the Pb/Sn interphase boundaries and occurs by grain boundary sliding (GBS) accompanied by sintering micropore processes under the action of the capillary forces on the Pb/Sn IB. During severe plastic deformation of Sn-Pb eutectic phase transition in the Sn grain boundary occurs. This defor…
Direct observation of strain-induced non-equilibrium grain boundaries
2015
Abstract The grain boundary (GB) wetting by the melt and second solid phase has been studied in the Sn–Pb system both in equilibrium conditions and during continuous strain. The percentage of Sn/Sn GBs completely wetted by the melt increases from 80% at eutectic temperature Te=183 °C to 100% at 220 °C. The percentage of Pb/Pb GBs completely wetted by the melt increases from 0% at Te to 100% at 270 °C. Below Te only incomplete wetting of Pb/Pb GBs by solid Sn and Sn/Sn GBs by solid Pb has been observed after long annealing. However, during strain the lattice dislocations are continuously absorbed by GBs increasing the GB energy. As a result, the complete wetting of such non-equlibrium Sn/Sn …