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  • 1
    Electronic Resource
    Electronic Resource
    Positron annihilation study of microvoids in centrifugally atomized 304 stainless steel (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2489-2495 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Positron trapping in microvoids was studied by positron-lifetime and positron Doppler line-shape measurements of centrifugally atomized 304 stainless-steel powder, which was hot-isostatically-press consolidated. This material contained a concentration of several times 1023/m3 of 1.5-nm-diam microvoids. Positron annihilation was strongly influenced by the microvoids in that a very long lifetime component τ3 of about 600 ps resulted. The intensity of the τ3 component decreased with decreasing number density of 1.5 nm microvoids. The Doppler peak shape was found to be much more strongly influenced by microvoids than by any other defects such as precipitates or grain boundaries. In particular microvoids produced significant narrowing of the Doppler distribution shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354078
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  • 2
    Electronic Resource
    Electronic Resource
    Positron annihilation measurements of Pr-containing superconductor compounds (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5534-5539 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Positron annihilation lifetime and Doppler broadening energy spectra have been measured in Pr-containing YBa2Cu3O7−δ as a function of temperature between 18 and 295 K. The defect-related positron lifetime component τ2 was independent of temperature for the PrBa2Cu3O7−δ compound and was very close to the value τ1 associated with bulk or defect-free material. These results indicate that the structure of this compound is nearly free of defects which trap positrons and that there is no electronic structure change during cooling. There was a slight temperature dependence below Tc for the Y0.5Pr0.5Ba2Cu3O7−δ compound. It was also found that a change in the positron Doppler line-shape parameter S occurred at the superconducting transition temperature for 0.5 Pr-containing compound but not for the 1.0 Pr-containing compound. These results show that the average electron momentum at the annihilation sites increases as temperature is lowered across the superconducting transition range for the 0.5 Pr-containing compound but not for the PrBa2Cu3O7−δ compound. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359672
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  • 3
    Electronic Resource
    Electronic Resource
    ION IMPLANTATION EFFECTS ON FATIGUE AND SURFACE HARDNESS (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 3 (1980), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1980.tb01367.x
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  • 4
    Electronic Resource
    Electronic Resource
    IMPROVEMENT OF FATIGUE LIFE OF 1080 STEEL BY THERMOMECHANICAL PROCESSING (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 1 (1979), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Many thermomechanical treatments (TMT) have been applied in the past to alloys in order to improve the balance between various static mechanical properties. The current research has applied a given type of TMT to the improvement of fatigue behavior in eutectoid steel. The TMT involved the cold rolling of annealed eutectoid steel to a reduction in thickness of 75% followed by rapid heating in liquid lead to a temperature just above the A1 temperature for a short time period and an air cool to room temperature. This type of TMT produces very oriented cementite in recrystallized ferrite. Plane bending cantilever fatigue tests with constant maximum load were run at 30 Hz and zero mean stress (R=−1·0). In terms of S–N fatigue curves the annealed condition is inferior to both the TMT and cold rolled conditions, however, there is no apparent advantage of the TMT over the cold rolled condition. There is, however, a considerable advantage in the TMT which becomes evident with normalization of all S–N curves with respect to the ultimate tensile strength. One thus finds that the TMT is quite superior, on an equivalent strength basis, to both the cold rolled and annealed conditions. The same was true on a basis of hardness normalization. This means that by TMT one can produce fatigue properties in a material of much higher formability which are equivalent to or better than those in a cold rolled material. Samples oriented in the cross-roll direction had total fatigue lives longer than for those oriented in the roll direction. This is explained in terms of mechanical fibering of pearlite colonies and inclusions, and by a crystallographic texturing of the ferrite matrix. TMT strength is a result of austenite grain size refinement, reduction of interlamellar spacing, fiber strengthening and both solid solution and precipitate hardening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1979.tb00394.x
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  • 5
    Electronic Resource
    Electronic Resource
    X-ray Asterism and Work-hardening in Crystals (1963)
    [s.l.] : Nature Publishing Group
    Nature 200 (1963), S. 254-255 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It was found possible to grow single crystals of commercial 'Alcoa 2011' alloy by the strain anneal technique in spite of the high impurity concentration. The nominal composition of this alloy is copper 5.5 per cent lead 0.5 per cent, bismuth 0.5 per cent, silicon 0.4 per cent, iron 0.7 per cent, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/200254b0
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  • 6
    Electronic Resource
    Electronic Resource
    Stress Concentration in Concrete (1964)
    [s.l.] : Nature Publishing Group
    Nature 203 (1964), S. 1374-1375 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In an attempt to find an explanation, tensile tests were carried out on plain thin concrete specimens, using a lazy tongs gripping device developed in the Engineering School and described previously elsewhere2 (Fig. 1). The purpose was to ascertain the effects of holes of various shapes on the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2031374a0
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  • 7
    Electronic Resource
    Electronic Resource
    Correlation of X-ray and electron microscopic studies of fatigue (1975)
    Springer
    International journal of fracture 11 (1975), S. 251-255 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé Le mémoire donne des éclaircissements sur les modifications substructurales qui se produisent en cours de fatigue d'alliages Ni-Co comportant différentes énergies de défauts d'empilement. En particulier, il traite de la manière dont la microscopie électronique par transmission et par sonde est à même d'élucider les résultats d'une étude substructurale précédente, au cours de laquelle on a eu recours à la technique des rayons X pour étudier les modifications de dimensions de particules durant l'essai de fatigue.
    Abstract: Zusammenfassung Dieser Bericht gibt eine Erläuterung für substrukturelle Änderungen unter Müdigkeit in Ni-Co Legierungen mit verschiedener Fehlerhäufungsenergie. Im besonderen wird gezeigt wie durch Transmissions-und Sondierungsmikroskopie eine frühere sustrukturelle Forschung, begründet auf die Änderung der Grösse von X-Strahlenpartikeln unter Müdigkeit, erklärt werden kann.
    Notes: Abstract This paper concerns the clarification of substructural changes occurring during fatigue in Ni-Co alloys of different stacking fault energy. In particular the paper deals with how transmission and scanning electron microscopy might elucidate an earlier substructural study based on changes of X-ray particle size during fatigue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00038892
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  • 8
    Electronic Resource
    Electronic Resource
    Precipitate strengthening mechanisms in magnesium zinc alloy single crystals (1969)
    Springer
    Journal of materials science 4 (1969), S. 861-872 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mechanical behaviour of Mg-5.1 wt % Zn alloy single crystals was studied in the 4.2 to 300° K temperature range. Quenched crystals have activation energies and volumes best associated with the cutting of small clusters of Zn atoms by dislocations. Fully hardened crystals contain fine β 1′ and occasionalβ 2′ precipitates with an averageβ 1′ interparticle spacing of 330 to 660 Å. Strengthening in these crystals is mainly ascribed to the cutting of β 1′ particles by dislocations. In the overaged condition β 1′, β 2′ and equilibrium β particles are present and lead to a considerable temperature-dependence unusual for an overaged condition. Analysis of this temperature-dependence suggests that below 77° K the relatively easy cutting of β 1′ particles by dislocations takes place in addition to the cutting of β 2′ and β particles. Above 77° K the difficult cutting of β 2′ and β particles alone controls the deformation, β 1′ being more easily cut with the aid of thermal fluctuations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549777
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  • 9
    Electronic Resource
    Electronic Resource
    Grain growth of chemical vapour deposited tungsten-22 wt % rhenium alloy (1973)
    Springer
    Journal of materials science 8 (1973), S. 559-564 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The structures of chemical vapour deposited (CVD) tungsten and a tungsten-22 wt % rhenium alloy in the as-deposited condition, were studied by scanning and transmission electron microscopy. Deposition occurs by the advancement of ledges up the {111} surfaces of four-sided pyramids. Grain growth was studied in the alloy at thirteen temperatures between 1400 and 2780°C. For annealing times of less than 1 h the apparent activation energy was 62±2 kcal mol−1. After several hours at temperatures above 2270°C the rate of grain growth decreased because of the development of bubbles at grain boundaries. Lamellar composition fluctuations were noted metallographically and by electron probe microanalysis. For CVD tungsten, the widening of columnar grains was studied at ten temperatures between 1290 and 2555°C. The rate of increase of columnar grain width became significant only at temperatures above 1980°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00550460
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of precursor history on synthesis of high-T c BPSCCO superconductor (1996)
    Springer
    Journal of materials science 31 (1996), S. 2349-2352 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract High-T c lead-doped BSCCO superconductors (BPSCCO) were prepared from precursors of three different histories. The method, which combined three kinds of calcined powders, decreased the total sintering time for the formation of high-T c BPSCCO superconductor phases relative to other methods based on one type of powder. The proportion of secondary phase, such as Ca22CuO3 was also reduced. As a result, the transition temperature,T c, from the current method is higher than for the latter fabrication methods. Thec-axis parameters of BSCCO superconductors from different precursors were compared. The average X-ray particle size of each phase in the bulk sample was calculated from the Scherrer formula. Finally, the surface morphology and composition of BPSCCO were examined by SEM and energy dispersive spectrometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01152945
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