The parameters of the solidus and liquidus phase transitions for TaC_x, HfC_x and ZrC_x are studied using a laser heating technique. A special emphasis is given to the accurate measurement of temperature and determination of spectral emissivity in course of the laser heating using advanced multichannel pyrometry. The phase transitions corresponding to the solidus and the liquidus are determined by means of the laser-probe reflectometry and by the peculiarities in the behaviour of spectral emissivity in the vicinity of the phase transitions and by the high-speed video recording of the melt formation and freezing. New data on solidus and liquidus parameters for the Zr–C system in the homogeneity domain (solid solution) are presented. The temperatures of congruent melting of super-refractory carbides TaC and HfC are determined along with the data on their solidus and liquidus lines close to the composition of congruent melting.

Ball-milled hydroreactive powders of Mg-Al scrap with 20 wt.% additive (Wood’s alloy, KCl, and their mixture) and with no additives were manufactured. Their hydrogen yields and reaction rates in a 3.5 wt.% NaCl aqueous solution at 15–35 °C were compared. In the beginning of the reaction, samples with KCl (20 wt.%) and Wood’s alloy (10 wt.%) with KCl (10 wt.%) provided the highest and second-highest reaction rates, respectively. However, their hydrogen yields after 4 h were correspondingly the lowest and second-lowest percentages—(45.6 ± 4.4)% and (56.0 ± 1.2)% at 35 °C. At the same temperature, samples with 20 wt.% Wood’s alloy and with no additives demonstrated the highest hydrogen yields of (73.5 ± 10.0)% and (70.6 ± 2.5)%, correspondingly, while their respective maximum reaction rates were the lowest and second-lowest. The variations in reaction kinetics for the powders can be explained by the difference in their particle sizes (apparently affecting specific surface area), the crystal lattice defects accumulated during ball milling, favoring pitting corrosion, the morphology of the solid reaction product covering the particles, and the contradicting effects from the potential formation of reaction-enhancing microgalvanic cells intended to induce anodic dissolution of Mg in conductive media and reaction-hindering crystal-grain-screening compounds of the alloy and metal scrap components.

This study is devoted to the hydrothermal oxidation of aluminum—the exothermic process in which hydrogen and aluminum oxide (or hydroxide) are produced. In this work, the influence of the chemical purity of aluminum on the conversion degree of coarse aluminum at hydrothermal oxidation was studied. Distilled water and coarse granules of aluminum with an average size of ~7–10 mm and three different aluminum purities—99.7, 99.9, and 99.99%—were used in the experiments. The oxidation experiments were carried out inside a 5 liter autoclave in an isothermal mode at temperatures from 200 to 280 °C, with a step of 20 °C. The holding time at the set temperature varied from 4 to 10 h. It was shown that the chemical purity of aluminum considerably influences the oxidation kinetics. More chemically pure aluminum oxidizes much faster, e.g., at a temperature of 280 °C and a holding time of 10 h, the conversion degree of granules with a chemical purity of 99.9% and 99.7% was less than 2%, while 99.99% aluminum was almost fully oxidized. The conversion degree of 99.99% aluminum decreased with the reduction in temperature and holding time, to 66–68% at 280 °C, 4 h, and 2–3% at 200 °C, 10 h.

The shock compression of porous nickel from nanosized particles nNi was studied at a pressure range of 4–61 GPa. The average size of the nNi particles was 50 nm, and the porosity of the samples was 50%. Plane shock waves in the samples were generated by the impact of aluminum plates accelerated to velocities ranging from 0.8 to 5 km/s. Laser interferometry was used to monitor particle velocity histories at the interface between the samples and water or LiF windows. The data obtained at pressures below 8 GPa showed a complex shock wave profile with the formation of an elastic precursor wave. The shock Hugoniot and data on the expansion isentropes were obtained. The Hugoniot of nanosized nNi coincided within the experimental errors with the Hugoniot of micron-sized nickel. The Hugoniot calculated on the basis of the equation of state for porous nickel was in good agreement with that of experimental data. It has been established that in the middle pressure range (20–35 GPa), the expansion isentropes in the “pressure–particle velocity” coordinates become noticeably flatter with a significant increase in the particle velocity. The reason for this phenomenon is still unclear. An assumption was made about the onset of particle melting upon reaching pressures above 15 GPa.

The effect of thermohydrogen treatment and vacuum ion–plasma nitriding on the determination of the volume and surface structure of ball heads made of Ti–6Al–4V alloy was studied. It was found that the submicrocrystalline structure formed in the head during thermohydrogen treatment makes it possible to achieve hardness values of 39–41 units HRC and a surface roughness of 0.02 μm. It was shown that the creation of a modified layer consisting of ε (TiN) and δ (Ti₂N) titanium nitrides on the surface of a ball head and the solid interstitial solution of nitrogen in α-titanium makes it possible to completely eliminate material wear when testing for friction on ultra-high-molecular-weight polyethylene. The equivalent analysis was also conducted with a ball head that had been implanted in a human body for 12 years. It was found that the change in the color of the head, from slightly golden after nitriding to metallic, is due to the formation of an oxynitride nanoscale layer on the surface. It was shown that in contrast with films made of titanium oxide, the film developed in this study has high wear resistance.