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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5724-5731 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The role of structural relaxation in the plastic flow behavior of metallic glasses is analyzed both theoretically and experimentally. The characteristic time of structural relaxation is calculated as a function of glass thermal prehistory. It is revealed that heating above the room temperature by several tens of Kelvins results in a sharp, by several orders of magnitude, decrease of this time. It is argued that localized "inhomogeneous" dislocation-like flow occurs on loading if the characteristic time of structural relaxation is much greater than the characteristic loading time, while "homogeneous" viscous deformation is observed in the opposite case. Precise measurements of acoustic emission in a Co-based metallic glass being loaded at different temperatures and strain rates are employed for verification of this statement. It is shown that the inhomogeneous → homogeneous flow transition occurs at temperatures somewhat higher than T=400 K, and the transition temperature increases by (approximate) 40 K as the strain rate increases by two orders of magnitude. Theoretical estimations show that for the inhomogeneous flow the characteristic time of structural relaxation in the loaded state is indeed much greater than the characteristic loading time. It is concluded that the kinetics of structural relaxation determines the flow mode of metallic glasses in a unique manner. The kinetically "frozen" structural relaxation gives rise to a crystalline-like localized flow under load while intensive structural relaxation facilitates a viscous glass-like behavior. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Physics of the solid state 41 (1999), S. 1989-1994 
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract On the basis of a calculation of the structural relaxation rate and an experimental acoustical-emission determination of the temperature of the transition from localized to uniform flow it is argued that the type of plastic deformation of metallic glasses is uniquely determined by the kinetic structure of the relaxation. In the case of a kinetically hindered structural relaxation, which is characteristic for tests of initial samples at temperatures T〈380–420 K, a localized dislocational deformation is realized. At higher temperatures, “memory” of the thermal prehistory of the samples is lost (aging at room temperature), the structural relaxation rate grows abruptly and plastic flow becomes uniform viscoplastic flow.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Physics of the solid state 39 (1997), S. 787-790 
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements have been made of the acoustic emission that occurs during the plastic deformation of metallic glass subjected to various heat treatments. It is shown that for the same temperature and deformation rate it is possible to have either homogeneous flow with no acoustic emission or localized flow accompanied by intense discrete acoustic emission, depending on the preliminary annealing conditions. From an analysis of the experimental results, it is deduced that the nature of the plastic flow of metallic glasses is determined by the structural relaxation rate at the experimental temperature and the conditions of intense structural relaxation, that plastic flow is homogeneous viscoelastic, and, under the conditions of kinetically inhibited structural relaxation, that it is localized and occurs by a dislocation-like mechanism.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1562-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Doklady physics 45 (2000), S. 620-622 
    ISSN: 1562-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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