Presented results of active resistance frequency dependence measurements of a circular cross-section aluminum and copper conductors with a various diameter in a wide frequency range from 20Hz to 2MHz. Using the skin effect simulation we show that for all types of wires an increased active resistance observed, compared to the theoretical values in the frequency range above 200 kHz, where the skin layer thickness becomes less than 200 μm. This phenomenon may be associated with the manufacturing process of a metal wire by drawing through a die, when defects are formed in the near-surface layer, leading to its increased resistivity.
For high-strength titanium VT1-0, the ultrafine-grained structure of which was obtained by mechanical-thermal treatment using the methods of helical and longitudinal rolling followed by annealing to relieve stress of the first kind. The effect of long - term loading in the creep mode at elevated temperature on the size and shape of grains has been studied. A similar study was previously carried out for recrystallized coarse-grained titanium transferred from the ultrafine-grained state by isothermal annealing. Based on the data obtained in the work and the previous results of the authors, the factors affecting the mechanical stability (durability) of ultrafine-grained metals obtained under severe plastic deformation were analyzed.
The results of a study of aluminum alloy AD1 in four structural states before and after severe plastic deformation are presented. Both the initial coarse-grained state (supply state) and three fine-grained states, which differ from each other in the method of obtaining, are considered. Elastic and microplastic properties (modulus of elasticity, decrement of elastic vibrations, microplastic deformation) were determined by the acoustic method of a composite vibrator. It is shown that the modulus of elasticity changes to a large extent under the influence of the evolution of internal stresses; the attenuation of ultrasound after severe plastic deformation increases due to an increase in the area of grain boundaries. Key words: AD1 aluminum, modulus of elasticity, microcrystalline aluminum, decrement of elastic vibrations, microplastic deformation.
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