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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3450-3453 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural development with milling time during mechanical alloying of niobium and tin powders, of average composition Nb3Sn, was followed by x-ray diffraction. The elemental powders initially alloy mechanically to form an A15 structure phase. With continued milling, the A15 phase transforms to an amorphous structure. The kinetics of the structure changes are dependent on the milling media and atmosphere. The measured lattice parameter a0 for the A15 phase prepared with tungsten carbide milling media in an argon atmosphere agrees with the literature value of a0 for bulk Nb3Sn. However, milling with steel media introduced significant contamination by iron and an anamolous expansion of the A15 phase lattice. Amorphization of the A15 phase is believed to be due to the creation of a critical defect concentration by the mechanical deformation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 109-111 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the electrical properties of small parts of single grain boundaries in melt textured YBa2Cu3Ox. Similar measurements on grain boundary networks were also made to obtain composite properties. The results of Tc measurements and current-voltage characteristics in zero and small magnetic fields are presented. The R(T) characteristics suggest that there is second phase segregation in some parts of the grain boundary area. The current-voltage characteristics showed three different types of behavior: Resistive, Josephson-like, and flux flow. The Ic(B) data of Josephson junctions suggest that nonsuperconducting inclusions divide the grain boundaries into smaller single junctions.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 823-825 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tensile tests were performed for Zn at room temperature, which show elongations of 110%–20% for average grain sizes of 240–23 nm, respectively. The ductility of ultrafine-grained and nanocrystalline Zn was found to decrease with grain size refinement. The deformation mechanisms in ultrafine-grained Zn are believed to be a mixture of grain boundary sliding of small nanograins and intra-grain dislocation creep within the large grains. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 19 (1989), S. 121-143 
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    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 Mechanical alloying was used to synthesize NixZr1−x alloys from mixtures of intermetallic compound powders, and also from mixtures of intermetallic compound powders and pure elemental powders. The mechanically alloyed powders were amorphous in the range 0.24 ⩽ x ⩽ 0.85. This range is larger than amorphous alloys produced by the melt-spinning technique and mechanical alloying of elemental crystalline powders. Two-phase mixtures of the amorphous phase and the corresponding crystalline terminal solid solution were formed in the range 0.10 ⩽ x ⩽ 0.22, and x=0.90. It is found that the morphological development during mechanical alloying of these powders is different from mechanical alloying using only pure ductile crystalline elemental powders. The thermal stability has been investigated. The enthalpy and activation energy of crystallization for Ni-Zr amorphous powders prepared by mechanical alloying are lower than those for melt-spun samples of the same composition. The crystallization temperature of the mechanically alloyed Ni-Zr amorphous powders is higher than that of meltspun samples in the composition range Ni20Zr80 to Ni33Zr67 and Ni40Zr60 to Ni60Zr40. The presence of tiny crystallites as nucleation centres and high oxygen levels in the mechanically alloyed amorphous alloys might be responsible for the differences in crystallization behaviour. A new crystalline metastable phase was observed during crystallization studies of Ni24Zr76 amorphous powder.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 18 (1983), S. 759-765 
    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 Superconducting transition temperatures (T c) were measured for a series of Mo-P-B alloys in the Mo-rich corner of the ternary system. The alloys were studied in two forms: (a) slowly cooled after induction melting, and (b) rapidly quenched in an arc hammer apparatus. The rapid quenching produced an amorphous structure, but most of the alloys also contained some crystalline material, indicating that this system is not conducive to easy glass formation. Ternary slowly cooled crystalline alloys in the concentration range 20 to 30 at % phosphorus and 10 to 20 at % boron had relatively highT c values of 9.6 to 9.9 K; higher than for either the Mo-P or Mo-B binary systems.T c values up to 9.02 K were observed for completely amorphous foils, consistent with the previously reported maximumT c values for amorphous alloys in this system. This remains the highestT c reported for a metallic glass. All of the rapidly quenched foils were brittle.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 18 (1983), S. 2126-2134 
    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 A series of amorphous Mo-N films was prepared by electron beam evaporation of molybdenum in varying partial pressures of nitrogen and deposited onto substrates cooled to about 80 K. The alloy films were characterized by X-ray diffraction, the superconducting transition temperature,T c, and the crystallization temperature,T x. The maximumT c (8.3 K) and sharpest transition occurred with the minimum nitrogen pressure necessary to form the amorphous structure, as revealed by X-ray diffraction. After annealing the as-deposited films, both bcc and fcc phases were found with the bcc/fcc ratio decreasing with increasing nitrogen partial pressure. Differential scanning calorimetry (DSC) measurements showed significant differences in the shape of peaks associated with either bcc, bcc+fcc, or fcc phases. The temperature,T x, associated with the fcc crystallization increased with nitrogen content. Heats of crystallization had an average value of about 63 J g−1. Changes in position of the first amorphous X-ray diffraction peak showed that the amorphous structure was expanded by increasing nitrogen content.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 32 (1997), S. 3835-3839 
    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 Different solid-state reactions, i.e. Fe+SiC→Fe3C+Fe(Si), and Fe+SiC→Fe3Si+Fe2Si+C, were found in mechanically alloyed nanocrystalline Fe/SiC composites induced by prolonged milling or heat treatment, respectively. The solid-state reaction between nanocrystalline iron and SiC upon heating is greatly enhanced when compared with that between bulk iron and SiC. It is believed that the prolonged milling-induced reaction is related to the changed thermodynamics and kinetics while the heat-treatment-induced reaction, completed during a short time, is attributable to the changed reaction kinetics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 19 (1975), S. 493-512 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: A comparison has been made of four methods of measuring the critical current density J c in hysteretic type II superconductors, having a wide range of κ and J c values, in magnetic fields up to 70 kOe. Two of the methods, (a) resistive measurements and (b) magnetization measurements, were carried out in static magnetic fields. The other two methods involved analysis of the response of the sample to a small alternating field superimposed on the static field. The response was analyzed either (c) by measuring the third-harmonic content or (d) by integration of the waveform to obtain a measure of flux penetration. The results are discussed with reference to the agreement between the different techniques and the consistency of the critical state hypothesis on which all these techniques are based. It is concluded that flux-penetration measurements by method (d) provide the most detailed information about J c but that one must be wary of minor failures of the critical state hypothesis. Best results are likely to be obtained by using more than one method.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 19 (1998), S. 557-561 
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Incorporation of liquid crystalline polymers (LCPs) into commodity polymers remains a challenge in the design of high-performance, low-cost polymeric blends. Blends of a thermoplastic polymer and a nematic LCP are produced here by mechanical alloying. Functionality sensitive X-ray microscopy reveals LCP dispersions as small as 100 nm in diameter. Intimate mixing remains upon subsequent melt processing, indicating that mechanical alloying is suited for applications such as recycling.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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