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In this paper, Fe10Co25Ni34Cu23Al8 high-entropy-alloy nanoparticles have been synthesized by the in situ instantaneous electrical wire explosion method. Based on the thermodynamic parameters of the face-centered cubic phase of high-entropy-alloy, the parameters of the five kinds of wires were calculated and controlled, and the stable face-centered cubic structure with good crystallinity was synthesized in one step. The influence of the energy deposition during the electrical explosion on the nanoparticles and their electromagnetic absorption performance was explored. The results show that the face-centered cubic structure high-entropy-alloy with high crystallinity has better electromagnetic wave absorption performance when the energy deposition of the wires is increased. The minimum reflection loss can reach −39.37 dB at 15.34 GHz when the thickness is 1.9 mm and the effective absorption bandwidth is 6.63 GHz. It can provide a strategy for the microstructure and morphology design of high-entropy-alloy nanoparticles in electromagnetic wave absorption and magnetism in the electronics industry. [ABSTRACT FROM AUTHOR]

Electrical explosion of wires (EEW) can be utilized as an efficient method to prepare nanopowders of metal, metal oxide, metal alloy, and so on, and the behavior of exploding wires varies greatly with different load and circuit parameters. In this paper, the relationship between discharge modes of EEW and load parameters (length and diameter) was studied during the preparation of Al nanopowders via EEW in argon gas. The experimental results showed that with fixed wire length and increasing diameter, the EEW will successively show the feature of current pause, current dwell, current pause again, and finally “being matched”; and for fixed wire diameter, there is a “critical length” of wire which divides the current-dwell mode and the current-pause mode. The critical length as a function of wire diameter peaks between 0.2 and 0.3 mm for the charging voltage of 11.5–20 kV (2.6- $\mu \text{F}$ capacitor); and the specific heat (deposited energy divided by sublimation energy) of wires was approximately 1 at the peaks. [ABSTRACT FROM AUTHOR]

The discharge plasma channel (DPC) evolution process is observed by taking time-series self-emission intensified charge-coupled device (iCCD) photos and simultaneous shadow images. By adding neutral density filters before iCCD, the subtle structure of the DPC self-emission is observed. It is interesting that a treelike structure is observed soon after the voltage breakdown. Long exposure time photos demonstrate that this structure existed for hundreds of nanoseconds. An inner homogeneously luminous column arises latterly, forming a two-layer self-emission structure. Then, this column gradually occupies the whole DPC. Shadow images show that the expanding DPC maintains good axial uniformity, manifesting the long-standing uneven treelike structure only has limited impact on the energy distribution and the expansion process. The calculated expansion rate reaches its maximum value (4.75 km/s) not at the power peak, but 0.24 $\mu \text{s}$ after that. Then, the expansion rate undergoes fast drop and slow decline. In addition, it seems that the distributions of related plasma parameters experience an evolution from nonuniform to uniform. [ABSTRACT FROM AUTHOR]

The evolution of single- and dual-wire Z-pinch of 8- \(\mu \) m W was investigated by X-ray backlighting using an X-pinch X-ray source. The experiments were carried out on the pulsed-power generator PPG-I (400 kA/500 kV/100 ns), which was designed and constructed by the Department of Electrical Engineering of Tsinghua University. To scale the mass density distributions at different explosion time, a mass step wedge including eight tungsten layers was fabricated and inserted between the object Z-pinch and the X-ray film. By a large number of imaging experiments, the physical images of coronal plasma formation and interwire plasma merging were obtained. Based on the X-ray photos of 8- \(\mu \) m W and mass step wedge, the mass density distributions at different explosion time were drawn, and the conductance curve of time dependence of 8- \(\mu \) m W was also calculated using waveform of voltage and current. [ABSTRACT FROM PUBLISHER]

Wire explosion is the initial stage of the development of wire array Z-pinch load driven by high pulsed current. Based on the pulsed power generator PPG-1 (400 kA/100 ns), the process of 10- \(\mu \) m-W wire explosion at tens of kiloamperes was investigated. The time sequence images of wire explosion were obtained by X-ray backlighting with X-pinch X-ray point source, and the mass density distribution of the exploding wire at a certain time was calibrated by method of grayscale contrast based on a particular step wedge filter. By image processing of the time sequence images of wire explosion, the evolution of mass density distribution of wire explosion was presented. [ABSTRACT FROM PUBLISHER]

This study demonstrates fabrication of FeCoNi magnetic nanoparticles by joint electrical explosion of wires for electromagnetic wave absorption applications. An increase in the energy storage capacity of the capacitors can increase the maximum reflection loss of the nanoparticles and shift the corresponding frequency in the low-frequency direction, but has no significant effects on the maximum bandwidth. The minimum reflection loss of the magnetic nanoparticles reaches − 50.2 dB at 6.8 GHz when the thickness is 2.5 mm, while the maximum effective absorption bandwidth reaches 8.1 GHz at a thickness of 1.5 mm. The wire explosion method, as an instantaneous synthesis method with a low cost, environmental friendliness, and high-output characteristics, provides a new approach to industrial batch preparation of microwave-absorbing materials. • Magnetic alloy nanoparticles FeCoNi successfully obtained by joint electrical wires explosion. • More uniform particles composition can be achieved by increasing discharge energy. • The maximum reflection loss is − 50.2 dB at 2.5 mm and the absorption bandwidth (<−10 dB) is 8.1 GHz at 1.5 mm. [ABSTRACT FROM AUTHOR]