[en] The atomic structure of a new ternary phase UFe₂Al₁₀ appearing in the U-Fe-Al system was determined using direct methods applied to X-ray powder diffraction data. High resolution electron microscopy combined with the methods of crystallographic image processing was used for the verification of the structural model. The UFe₂Al₁₀ phase is orthorhombic and belongs to Cmcm space group, its unit cell contains 40 Al, eight Fe, and four U atoms. The lattice parameters obtained after Rietveld refinement are: a=8.919 A, b=10.208 A, and c=9.018 A. The reliability factors characterizing the Rietveld refinement procedure are: R_p=5.9%, R_wp=8.1%, and R_b=2.9%

[en] Ion implantation was used to simulate neutron irradiation damage in Al-A5 alloys. The damage was investigated by scanning electron microscopy. H⁺ and He⁺ ions were implanted up to a dose of 2x10⁴ microcuri. It was found, that H⁺ ions caused the appearacnce of blisters and holes on the surface. The density of the blisters and holes is a function of implanted dose. The He⁺ ions caused sputtering of surface via flanking. (author)

No abstract available

[en] The impact of neutron irradiation on the internal microstructure, mechanical properties and fracture morphology of cold-worked Al-1050 and Al-6063 alloys was studied, using scanning and transmission electron microscopy, and tensile measurements. Specimens consisting of 50 mm long and 6 mm wide gauge sections, were punched out from Al-1050 and Al-6063 23% cold-worked tubes. They were exposed to prolonged neutron irradiation of up to 4.5x10²⁵ and 8x10²⁵ thermal neutrons/m² (E < 0.625 eV) for Al-6063 and Al-1050, respectively, at temperatures between 41 and 52 degree. The tensile specimens were then tensioned until fracture in a hydraulic tension machine at a strain rate of 2x10^-3 s^-1. In general, the uniform and total elongation, the yield stress, and the ultimate tensile strength increase as functions of fluence. However, for Al-1050 a decrease in the ultimate tensile strength and yield stress was observed up to a fluence of 1x10²⁵ thermal neutrons/m² which then increase with thermal neutrons fluence. Metallographic examination and fractography for Al-6063 revealed a decrease in the local area reduction of the final fracture necking. This reduction is accompanied by a morphology transition from ductile transgranular shear rupture to a combination of transgranular shear with intergranular dimpled rupture. The intergranular rupture area increases with fluence. In contrast, for Al-1050, fracture morphology remains ductile transgranular shear rupture and the final local area reduction remains almost constant No voids could be observed in either alloy up to the maximum fluence. The dislocation density of cold-worked Al was found to decrease with the thermal neutron fluence. Prolonged annealing of unirradiated cold-worked Al-6063 at 52 degree led to similar results. Thus, it appears that, under our irradiation conditions, whereby the temperature encompassing the samples increases the exposure to this thermal field is the major factor influencing the mechanical properties and microstructure of aluminum alloys

[en] Published in summary form only

[en] Radiation effects in nuclear fuel elements were studied by fractography. Fuel elements were experimentally irradiated at various doses at the IRR-2. Irradiated, as well as unirradiated fuel elements, were bent till fracture with a bending press. The fractured surfaces were examined by standard replication techniques. The structures reveal the same morphological zones as in standard tensile fractures. The crack origin zone (fibrous zone) appears near the fuel indent. The radial marks zone starts near the origin and covers about 2/3 of the cross-sectional area. The third zone (shear rupture zone) has a bump, sometimes 1 cm high. The crack origin zone is mainly brittle. As the crack propagates in the radial marks zone it becomes more ductile until its entirely ductile at the bump top. Beyond the bump it turns brittle again. (author)

[en] Multiphasic studies of the stomach were performed in 134 patients. The double-contrast, compression, mucosal relief, and full-column films obtained disclosed 82%, 65%, 62%, and 51%, respectively, of 153 lesions detected on multiphasic examinations. Detection of lesions by combinations of techniques relative to the multiphasic study was as follows: simple single-contrast and double-contrast examinations, 82%; various biphasic examinations, 89%, 91%, 97%, and 99%. The results indicate that no simple examination optimally detects gastric lesions, and that the more techniques employed, the more accurate the examination, to a point of diminishing returns

No abstract available

[en] The solidification of Al-U alloys at slow cooling rates was investigated using optical and scanning microscopy. Highly purity uranium (99.9%) and high purity aluminium (99.9%) or 'commercially pure' Al-A5 (Al-1050) alloy containing a maximum of 0.5% wt/o of other alloying elements were used to prepare Al-U alloys in a resistance furnace under controlled atmosphere. The observed eutectic composition for U-(Al-5) was 17±1 wt/o U, while that for U and pure Al was 19±1 wt/o U. These values are significantly different than the value of 13 wt/o U, reported in the literature. The eutectic morphology and its distribution depends on the type of the aluminium used in preparing the alloy. In both cases eutectic colonies were observed. In alloys prepared with pure Al, the eutectic colonies have a diameter less than 0.2 mm, display a lamellar morphology, and are homogenously distributed. In alloys prepared with Al-5, at list 4 different types of eutectic morphologies were observed. Some of the eutectic colonies have diameters as large as 2 to 3 mm. Some interesting nonequilibrium morphological features were observed in the specimen containing hypereutectic compositions. The above results are discussed on the basis of current solidification theories. (authors)

[en] The effect of neutron irradiation on cold worked, commercially pure A5 aluminum was investigated, utilizing scanning as well as transmission electron microscopy, and tensile measurements. During irradiation Si precipitates, while the dislocation density decreases suggesting a partial recovery. A threshold fluence of 2x10²¹ thermal neutrons/cm² was observed for nucleation of Si precipitation. No voids could be observed up to fluences of about 8x10²¹ thermal neutrons/cm². After an initial decrease in the ultimate tensile strength both ultimate tensile strength and elongation increase as functions of fluence. This is attributed to a combination of irradiation recovery and Si precipitation hardening. The mechanical properties are independent of the drawing direction. The results are discussed in terms of existing irradiation effect theories. (orig.)