Different-shaped ultrafine MoNbTaW high-entropy alloy powders were firstly prepared by a convenient mechanical alloying method. The phase composition and microstructure of the powders were characterized. The powders are ultrafine with nano-sized grains and a good homogeneous microstructure. All the powders have a single body-centered cubic solid solution phase and form the high-entropy alloy during mechanical alloying. These powders with different shapes are quite attractive for developing high-performance MoNbTaW high-entropy alloy bulk and coatings combined with a following sintering, spraying, or additive manufacturing technique.

This study investigates the effect of vanadium (V) addition on the hydrogen storage performance of Mg-Ni alloys prepared via high-energy ball milling (HEBM). The kinetic and thermodynamic properties of the composites were investigated by using analytical methods such as XRD, TEM, SEM, and PCT, and the modification patterns of Mg-Ni–based alloys with different contents of V particles were described. The results indicate that V does not alloy with Mg₂Ni but exists as interstitial particles, enhancing the microstructure and improving the hydrogen storage properties of the alloys. The alloy exhibits a flat pressure-composition curve, which indicates that the alloy reaches thermodynamic equilibrium during hydrogenation and the metallic phase coexists with the hydride phase. The apparent activation energy (E_des) for dehydrogenation decreased with increasing V content, from 32.04 kJ/mol for (Mg₂Ni)₉V₁ to 28.94 kJ/mol for (Mg₂Ni)₅V₅, suggesting improved kinetic properties. Thermodynamic parameters, such as enthalpy change (ΔH) and entropy change (ΔS), were also calculated, showing a reduction in ΔH with increasing V content, which enhances the hydrogen storage capacity. The findings demonstrate that the addition of V significantly improves the hydrogen storage performance of Mg-Ni alloys, making them promising as advanced hydrogen storage materials for practical applications.

A molten salt system was prepared using an optimized method. We studied the complex structure of Ir³⁺ ions in the molten salt system and the influence their concentration had on the quality of the coatings prepared via electrodeposition. Using TG-DSC and in situ XRD experiments, we studied the high-temperature characteristics and properties of IrCl₃ alongside its thermal stability. Using in situ XRD and Raman spectroscopy, we analyzed the Ir ions’ complex structure and the variation in the molten salt system at high temperatures. Finally, the changes in the Ir ion concentration in the molten salt system and the influence of the microstructure of the coatings’ surfaces were investigated under different anode conditions. IrCl₃ easily decomposes above 400 °C, and temperature increases accelerate the rate of this decomposition. When the NaCl-KCl-CsCl system is in a high-temperature, molten state, IrCl₃ forms stable complex structures (IrCl₆)³⁻ and (IrCl₆)²⁻, and the valence state of Ir will be transformed with the increase in temperature. Generating these complex structures is conducive to improving the Ir coating quality. During the electrodeposition process, too few Ir ions in the molten salt can lead to concentration polarization, affecting the quality of the coating. Application of the molten NaCl-KCl-CsCl system is conducive to the electrodeposition of Ir coatings in a suitable temperature range. At the same time, using Ir as the anode can enhance the quality of the coatings.