Fabrication of spherical particles with mixed amorphous / crystalline nanostructured cores and insulating oxide shells
By spark-eroding Fe75Si15B10 in water/ethanol mixtures, spherical particles with nanostructured cores consisting of mixed amorphous and crystalline phases were produced. The relative volume fractions of the amorphous and crystalline phases were dependent on the water/ethanol ratio. In the same process, continuous oxide layers were formed on the particle surfaces. The basic mechanisms responsible for the formation of the surface oxide layers and the core nanostructures were modeled. At frequencies ranging from 1 to 100 MHz, the combination of the core nanostructures and the insulating oxide shells yielded exceptionally low-loss magnetic behavior.
DISCRETE NONLINEAR-PROBABILISTIC MODEL OF THE EQUIVALENT ELECTRICAL RESISTANCE OF A LAYER OF METAL GRANULES
Two strategies for constructing nonlinear-probabilistic models of the equivalent electrical resistance of a layer of metal granules at their spark-erosion and plasma-erosion treatment and algorithms for their implementation are presented. A method for taking into account the parametric properties of such loads in their nonlinear and nonlinear-probabilistic models is described. Based on the data of direct experiments, the distributions of the electrical resistance of a layer of aluminum granules in tap water were obtained for eleven fixed values of the discharge current in it for both the leading and trailing edges of its pulses. The features of these distributions are described for different edges of the discharge current pulses. It has been proved that the obtained distributions can be adequately described by the normal law. The parameters of the normal law for each distribution obtained as a result of direct experiments are founded by the method of moments. A nonlinear-probabilistic model of the equivalent electrical resistance of a layer of aluminum granules in tap water is created, taking into account the main hysteresis of the dependence of resistance on current. It is shown that at large values of discharge currents, the nonlinear-probabilistic model of the equivalent electrical resistance of the layers of metal granules tends to degenerate into a nonlinear model. References 27, figures 4
Atomic structure of amorphous particles produced by spark erosion
The atomic structure of amorphous particles of composition ${\mathrm{Fe}}_{75}$${\mathrm{Si}}_{15}$${\mathrm{B}}_{10}$ produced by spark erosion was studied by the energy-dispersive x-ray diffraction technique and was compared to that of the amorphous ribbon of the same composition produced by melt spinning. It was found that the nearest-neighbor Fe-Fe correlation is almost identical for the ribbon and the particles of different sizes, whereas the second peak of the radial distribution function shows considerable differences among the samples. The result is consistent with decreased metal-metalloid compositional short-range order in the particles compared to that in the ribbon sample.