Diamane is a two-dimensional carbon-based structure coated with hydrogen atoms. The stiffness constants of diamane are studied by molecular dynamics simulation. These constants are used for an analytical calculation of Young’s modulus, Poisson’s ratio, and shear modulus. Two different morphologies are considered, namely, AA diamane and AB diamane. Moreover, both morphologies can contain hydrogen or be without it. It is found that pristine diamane without hydrogen demonstrates higher stiffness constants due to the changes in hybridization. At the same time, the difference in the values of the constants for the two diamane morphologies AA and AB is insignificant. All the obtained results are compared with elastic constants of graphene and diamond calculated by the same method and obtained from literature. Young’s modulus of pristine diamane equal to 1182 GPa is close to that of for graphene diamond.

Ni-Mn-Sn Heusler alloys exhibit a significant value of magnetocaloric effect. A disadvantage of these alloys is their high brittleness in the as-cast state, but their ductility can be increased by a thermomechanical treatment. The results of a study of thermal treatment for achieving a structure of Ni44.4Mn36.2Sn14.9Cu4.5 alloy applicable for further thermomechanical treatment are presented. It is shown that after argon-arc melting and cooling of the ingot in a water-cooled copper crucible, the structure is characterized by two phases that are quite similar in composition and have no clear phase boundaries. After homogenization annealing at 860°C for 24 hours and slow cooling, a two-phase state with regions enriched in Cu atoms is observed. It is possible to preserve the single-phase structure of the high-temperature state by quenching from the annealing temperature. In order to imitate the temperature regime of thermomechanical treatment, the alloy in the single-phase quenched state was subjected to annealing at 700°C for 1 hour and slow cooling. An analysis of the microstructure shows that, as a result, it remains in the same single-phase state. Thus, a mode of heat treatment of the Ni44.4Mn36.2Sn14.9Cu4.5 alloy, which makes it possible to achieve the applicable structure for further thermomechanical treatment, was selected.

Earlier studies have shown that it is possible to successfully obtain Ti6Al4V-Cu alloys with various copper concentrations using the double-wire electron beam additive manufacturing. Obtaining these alloys is of a practical interest for creating a titanium-base composite material with reduced risk of spontaneous combustion, which could be used in friction units at elevated temperatures. This article presents a study of the tribological properties of Ti6Al4V titanium alloy samples produced by layer-by-layer electron beam melting with the addition of Cu from a wire. The results of this work demonstrate an improved wear resistance of Ti6Al4V-Cu alloys. Such a result was achieved due to the grain refinement and precipitation of intermetallic Ti2Cu nanosized particles. For instance, the value of linear wear of alloys Ti6Al4V-6 wt.% Cu and Ti6Al4V-9.7 wt.% Cu is 46 % and 40 % less, respectively, as compared to the original alloy Ti6Al4V. It has been established that the plastic deformation penetration below the worn surface decreases with the increase in the concentration of copper in titanium alloy samples.

The formability of the novel Ti-1.5Al-1.5V-2.75Fe-3.0Mo-0.25Ni-0.1B alloy and the commercial Ti-6Al-4V alloy at 700°С was evaluated in the present study. Experiments have demonstrated the possibility of superplastic forming of both alloys with a fine-grained microstructure at 700°C and a constant argon gas pressure p = 2 MPa. However, the forming time for the novel alloy was only a few minutes (τ = 235 s), while for the Ti-6Al-4V it amounted almost 2.5 hours (τ = 8700 s). The better formability of the novel alloy at 700°С compared to the commercial one is in good agreement with the results of computer simulations performed earlier and is mainly due to an increased content of the β phase. Microstructural analysis showed that low-temperature superplastic forming was accompanied by the development of spheroidization and recrystallization processes. It is important that recrystallization did not lead to a significant grain growth and provided an increase in the structure homogeneity and randomization of the rolling texture. The most significant improvement of microstructure homogeneity after forming at 700°C was observed in the Ti-6Al-4V alloy with the initial partially recrystallized structure.

Influence of homogenizing annealing on the parameters of grain structure, phase constituents involving nanoscale aluminides of transition metals, hardness and corrosion resistance of the aluminum alloy 1570C (Al-5Mg-0.18Mn-0.2Sc-0.08Zr, mass.%) ingot was studied to optimize its heat treatment regimes according to a two-stage annealing scheme. At the first step, the ingot was annealed at 360°С for 6 hours (conventional route). At the second step, the annealing was performed at various temperatures in the range of 400 – 520°C for 1 hour. It was found, that additional high-temperature annealing resulted in some reduction in the alloy strength. However, it was quite effective to eliminate the chemical heterogeneity of the cast structure and increase the corrosion resistance maintaining grain size, dispersity and coherency of Al3(Sc, Zr) precipitates.

A comparative fractographic investigation of fracture in the temperature range from −186 to 100°C of the Charpy impact samples is performed for the reactor low-activation ferritic-martensitic steel EK-181 after its high-temperature thermomechanical treatment (HTMT) and traditional heat treatment (THT). The mechanisms of steel fracture are revealed depending on the impact test temperature and treatment mode. On the upper and lower shelves of the impact toughness temperature curve, the steel fractures by the mechanism of transcrystalline ductile dimple fracture and transcrystalline quasi-cleavage, respectively. In the intermediate region (in ductile-brittle transition area), fracture occurs by a mixed mechanism. The transition temperature to the brittle state is determined, at which the proportion of ductile and brittle fractures is the same (after THT it is −3°C; after HTMT it is −14°C). It is established that HTMT significantly changes the type of fracture of the impact samples in comparison with THT. The microstructure formed during HTMT with hot deformation of austenite leads to the appearance of a crack-arrester type of delamination during the impact tests in the cold brittleness region, favoring an increase in the fracture toughness of the steel at a lower ductile-brittle transition temperature.

In this paper we study titanium Grade4, magnesium alloy Mg-Zn-Ca, corrosion-resistant austenitic steel 08Kh18N9 for medical applications. The mechanical properties in tension, torsional strength, and cyclic crack resistance under different types of loading of steels are investigated. The results are compared for two states of steels: the initial coarse-grained (CG) state and ultrafine-grained (UFG) state produced by severe plastic deformation processing via equal-cannel angular pressing (ECAP). It is demonstrated that the ultrafine-grained materials have essentially better strength and lower sensitivity to cyclic overloads. It is concluded that all the studied UFG materials are more promising compared to CG ones for the manufacture of medical devices for various purposes, which experience various static and cyclic loads during operation.

The research was conducted to study the thermal conductivity of detonation nanodiamonds-based composites. Composite nanodiamond materials were obtained in the course of thermobaric sintering at the press-free high-pressure apparatus (BARS) under 5 GPa and at temperatures within the range of 1100 –1500°С. It was ascertained that unlike diamond monocrystals with their thermal conductivity reaching up to 2100 W / (mK), the thermal conductivity of a nanodiamond composite is considerably lower and does not go beyond 18 W / (mK). Specifically, the temperature dependence of the thermal conductivity coefficient of a nanodiamond composite is anomalous as compared to a similar dependence in diamond monocrystals. The thermal conductivity coefficient in diamond monocrystals grows in compliance with the rising temperature, whereas it shows practically no changes in a nanodiamond composite in the temperature range of 50 – 300°С. Such a temperature dependence of the thermal-conductivity coefficient is apparently related to the features of the phonon spectrum of diamond monocrystals. This feature is stipulated by the dependence of the phonon spectrum of nanocrystals on their size, represented by a set of phonon modes in the range of the wave vector 0 < q <1 / L, i.e., the size of a diamond nanocrystal of 4.5 nm is alleged to limit the excitation of harmonics during nanodiamond composite heating, as opposed to macroscopic crystals that demonstrate the excitation of higher-frequency phonon modes during temperature growing.

The influence of the morphology of polyaniline derivatives on the electrical conductivity, sensory sensitivity to air humidity of thin-film structures based on them, and the reaction to ammonia vapors has been investigated. Aniline derivatives, as well as polymers based on them, poly-2-[(2E)-1‑methyl-2‑butene-1‑yl]aniline and poly-2-(cyclohex-2‑en-1‑yl), were synthesized. Using a scanning electron microscope, the morphology of the surface of thin films obtained from a solution of synthesized polymers by centrifugation on sitall substrates was studied. Studying the nature of morphology is extremely important when creating sensory devices. On the basis of these polymers, samples of resistive thin-film structures were prepared, the dependence of their electrical conductivity on the relative humidity of the air and the dependence of the current passing through the sample with a change in the concentration of ammonia vapors were measured. The influence of the morphology of the surface of the films on the sensitivity of sensors to air humidity has been experimentally revealed and the prospects of using the studied films in humidity sensors have been shown. According to the experimental data, it can be seen that poly-2-[(2E)-1‑methyl-2‑butene-1‑yl] aniline film has the highest conductivity at the same values of relative humidity.