Russian Physics Journal最新文献

Effect of Si content on the patterns of deformation and fracture of Ti_{1–x–y–z}Al_xTa_ySi_zN coatings under uniaxial tension is investigated. The nanoindentation method has shown that the coating with z = 0.10 has the maximum hardness, which is caused by the formation of a thin grain-boundary amorphous SiN_x phase. At the same time, the Ti_0.35Al_0.40Ta_0.10Si_0.15N coating showed the highest fracture resistance and adhesive strength. It is found that this effect is due to the suppression of the growth of columnar grains in this coating and the formation of a two-phase amorphous-nanocrystalline structure, which makes it difficult for cracks to propagate.

For the first time, the synchrotron X‑ray diffraction is used to study the phase evolution in the Fe-Cr-Al(film)/Zr(substrate) system during its low-energy high-current electron beam (LEHCEB) processing. It is found that surface layer undergoes successive phase transformations with increasing number of pulses and the energy density of LEHCEB. Initially, only Fe-Cr-Al film melting occurs. Next, the gradual film dissolution and the amorphous Fe-Cr-Al-Zr phase formation takes place, followed by the nucleation and growth of FeZr₂ intermetallic compound. And finally, the formation the β‑Zr solid solution phase occurs. During the interruption of the LEHCEB process at different stages, it is possible to achieve desired phase composition and surface layer properties.

In this work, Zn-1Cu-1Mn and Zn‑0.8Al‑0.5Ag alloys are considered as alternative materials for producing ureteral stents. To improve the mechanical properties, these alloys were deformed by equal-channel angular pressing (ECAP). The microstructure, microhardness and strength are investigated after tensile tests. The effects of grain refinement and twinning on mechanical properties have been investigated and discussed. It has been established that the presence of twins in the initial microstructure of the alloys leads to the brittleness of the material, which can be eliminated through deformation processing. An increase in the volume fraction of the MnZn₁₃ phase has been observed in the Zn-1Cu-1Mn alloy, as well as a precipitation of the Ag₃Al and AgZn₃ phases in the Zn‑0.8Al‑0.5Ag alloy.

A non-perturbative model of a plane gravitational wave with dust matter and pure radiation is discussed. The form of the energy-momentum tensor of dust matter in a privileged coordinate system is obtained, where the model allows for an analytical integration of the equations of motion of test particles in the Hamilton-Jacobi formalism by the method of separation of variables. It is shown that this model leads to a contradiction and there is no solution to self-consistent field equations. This implies that the gravitational wave model should be more complex and include additional sources.

An overview of the elaboration of V. G. Bagrov’s remarkable results on the emission of a special type of electromagnetic radiation by a particle moving in a magnetic field, referred to as the spin light, is given. It is common knowledge that synchrotron radiation of an electron, in addition to the electron-charge contribution, also contains that of a spin magnetic moment, which is exactly the spin light. V. G. Bagrov was among the founders of the spin light theory; he investigated this kind of radiation for a neutral particle—a neutron in a magnetic field, in which case the emission represents a pure spin light. By an analogy, the problem of spin light radiation can be considered for another neutral particle—a neutrino. In this article we present the basic theoretical results and an application of the Spin Light of Neutrino phenomenon, which occurs when a Dirac neutrino moves in matter.

The paper prtesents classification of space-time metrics with the motion group G₃(VIII) acting on the non-null hypersurface. This classification complements the classification carried out by Petrov.

The results of experimental studies of the structural characteristics and mechanical properties of ATZ ceramic composites manufactured by an additive method are presented. It is shown that the average grain size of both oxides increases with the sintering temperature. An X‑ray diffraction analysis shows that the sintering temperature does not affect the crystal structure of the studied ceramic composites. The ATZ three-point bending tests demonstrated high flexural strength comparable to traditional methods.

The paper investigates the stability of the elastic-viscoplastic constitutive model providing a basis for multilevel crystal plasticity models of metals and alloys. The analytical methods of A. M. Lyapunov and the analysis of local model sensitivity to the perturbation of individual parameters are used. As a result, stability of the investigated model is demonstrated.

The broad aspects of the microstructure-strength relationship in friction-stir welding (FSW) are discussed. It is shown that FSW may promote both strengthening and softening effects, and the final strength of FSW joints may be sensitive to the initial material condition. In the case of a fully-recrystallized material, FSW may lead to the hardening effect due to the grain refinement. In the case of the work- or precipitation-hardened structural conditions, FSW may result in material softening due to recrystallization or precipitation coarsening/dissolution.

The results of experimental studies on the effect of nanosized silicon dioxide powder synthesized by different methods (sol-gel, high-energy electron beam and arc plasma evaporation methods) on the structure and physical-mechanical properties of cement compositions are presented. It is shown that the purity of nanosilicon dioxide has a significant effect on the properties of cement stone in the initial setting time. It is established that nano-SiO₂ synthesized by arc plasma evaporation allows increasing the entire system reactivity, which is a consequence of higher strength characteristics and the hydrophilic properties of cement, providing plasticizing properties of the binder. The matrix framework of the modified cement stone predominantly represents needle-shaped crystals of low-basic calcium hydrosilicate C‑S-H (1) ranging in the size from 3 to 20 µm. This structure allows forming a reinforced matrix framework of cement stone and thus increasing the bonding between particles. Modification of cement stone with nano-SiO₂ at a concentration of 0.03 wt.% allows achieving a strength increase of up to 40%.