Results 1 - 10 of 10685
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[en] In the previous work, the Al–50Si alloy with fine primary Si is prepared by a low-cost technology. In addition, the morphology of primary Si and the metamorphic mechanism as well as the thermal expansibility of alloy are also investigated in this work. The mean size of primary Si can obtain the min value of 33.82 µm when the content of modifier is 3%. The thermal expansibility of alloy decreases with the increasing of modifier. The influence of microstructure, solid solubility as well as porosity on the thermal expansibility are also studied in this research. Moreover, several theoretical models such as ROM model, Turner model, Kerner model and Schapery model are also used to predict the coefficient of thermal expansion (CTE) of alloy.
[en] The container opening exhibits at least one internal cylindrical face at the top, the plug exhibits an outer cylindrical face, the diameter of the external face of the plug is slightly larger than the diameter of the internal face of the opening, with the plug inserted by rapid heating of the upper part of the opening to cause its expansion and allow insertion of the plug, the internal face of the opening then pressing strongly against the outer face of the plug after the restoration of thermal equilibrium by interruption of heating, while the plug can be extracted in the same way by rapid heating of the top part of the opening. An electromagnetic coil supplied with a.c. power surrounds the top part of the opening to generate rapid heating with a surface effect
[fr]L'ouverture du conteneur presente a sa partie superieure au moins une face interne cylindrique, le bouchon presente une face externe cylindrique, le diametre de la face externe du bouchon est legerement superieur au diametre de la face interne de l'ouverture, la mise en place du bouchon s'effectuant par un chauffage rapide de la partie superieure de l'ouverture afin de provoquer sa dilatation permettant l'introduction du bouchon, la face interne de l'ouverture venant alors s'appuyer fortement contre la face externe du bouchon apres retablissement de l'equilibre thermique par suppression du chauffage, l'extraction du bouchon s'effectuant de la meme facon par chauffage rapide de la partie superieure de l'ouverture. Une bobine electromagnetique alimentee en courant alternatif entoure la partie superieure de l'ouverture pour creer un echauffement rapide a effet superficiel
[en] In contrast to the generally accepted practice for searching metallic glassformers by trial-and-error quenching, we propose using density and coefficient of thermal expansion of as-cast polycrystalline alloys as indicators of the glass-forming ability. We study experimentally these characteristics for Cu100−xZrx alloys over the whole concentration range and a wide temperature range from room temperature up to 1120 K. In the concentration range of 35 < x < 55 at% corresponding to high glass-forming ability, strongly non-monotonous behavior of both quantities is observed. We reveal that location of the extrema on concentration dependencies of both the coefficient of thermal expansion and the density deviation from the additive law correlates with those for critical thickness of Cu–Zr amorphous alloys. We argue that correlation between glass-forming ability and anomalous behavior of thermal expansion is because as-cast polycrystalline samples of glass forming alloys possess highly distorted structure, which cause phonon anharmonicity. Our findings propose new express method to search metallic alloys with high glass-forming ability. (paper)
[en] The invention is applied, in nuclear industry for closing shipping containers of spent fuel assemblies. The opening of the cask and the plug are metallic and with the same thermal expansion and the same low conicity. The two parts are assembled by cooling the male part and heating the female part
[fr]L'invention s'applique, dans l'industrie nucleaire, a la fermeture de conteneurs de transport d'assemblages combustibles irradies. La virole entourant l'ouverture et le bouchon sont metalliques et de meme coefficient de dilatation; la virole et le bouchon comportent des portees coniques de faible pente conjuguees, pour constituter une piece male et une piece femelle assemblees par frettage en dilatant la piece femelle par chauffage et/ou en contractant la piece male par refroidissement
[en] This paper discusses a non-contact optical technique, electronic speckle pattern interferometry, that is well suited for thermal deformation measurement without the need of any surface preparation and temperature compensating process. Also, three kinds of composite materials with fiber and epoxy -unidirectional laminates(16 and 16) and Cross-ply laminates([0/90]s) have been analyzed by ESPI to determine their thermal expansion behavior.
[en] The structure of single-grain Cd84Yb16 samples aligned along the twofold and fivefold axes has been followed from 300 to 1050 K using high-energy synchrotron X-rays. The quasicrystal phase is stable up to its melting temperature of 914 K and has a large linear thermal expansion of 37.1 ppm K-1 over this temperature range. The samples melt congruently over a temperature range of less than 1 K. The liquid is 7% less dense than the solid and, upon cooling from the melt, the quasicrystal phase directly solidifies within a 1 K interval. The amount of undercooling achieved, about 5-25 K, was dependent on the cooling rate. The total scattering function of the liquid is consistent with a dilute liquid Cd structure. These results agree with suggestions that the structure of the liquid must undergo reordering in order to form the solid phases. However, there is no compelling evidence for icosahedral short-range order in the liquid prior to the formation of the quasicrystalline structure.
[en] The presence of two phase transitions at temperatures of 498K and 673K was established by the method of differential thermal analysis (Dta), high-temperature dependences of the crystal lattice parameters, linear coefficients of thermal expansion, conductivity and dielectric permittivity by impedance spectroscopy in TlInTe2 crystals. The thermal effects of phase transitions are determined. As a result of X-ray diffraction studies of TlInTe2 crystals, it was established that the detected phase transitions occur without a change in the lattice type.
[en] This device includes a primary circuit, a primary fluid inlet chamber, a primary fluid outlet chamber and a secondary circuit composed of many tubes extending inside the elongated casing. The inlet and outlet chambers are each composed of a cylindrical casing, one end of which is connected to one of the tube plates by a thin wall in the shape of a convex quarter annulus and the other to one of the ends of the elongated casing by another thin wall in the shape of a convex quarter annulus
[fr]Dispositif de compensation des dilatations dans un generateur de vapeur. Il comprend un circuit primaire, une chambre d'entree du fluide primaire, une chambre d'evacuation du fluide primaire et un circuit secondaire compose d'une multitude de tubes s'etendant a l'interieur de l'enveloppe allongee. Les chambres d'entree et d'evacuation sont constituees chacune d'une enveloppe cylindrique dont une extremite est reliee a l'une des plaques tubulaires par une paroi mince en forme de quart de tore convexe et dont l'autre extremite est reliee a l'une des extremites de l'enveloppe allongee par une autre paroi mince en forme de quart de tore convexe
[en] By exploring a simple model of a negative thermal expansion (NTE) system, we introduce a phenomenological expression to describe the temperature dependence of the pressure-induced softening in NTE structures. (paper)