Vol 126, No 3 (2025)

The frequency and field dependences of the wave transmission and reflection coefficients of a composite material with cobalt nanoparticles in an opal matrix were measured at frequencies of 26–38 GHz. The phenomena of ferromagnetic resonance and antiresonance have been experimentally studied. The theoretical calculation of the dependences of the transmission and reflection coefficients on the magnetic field is performed. The specificity of antiresonance in a composite material has been revealed. The importance of taking into account the interference of waves in the nanocomposite is indicated. The field dependence of the depth of penetration of microwaves into the composite is calculated. Formulas for calculating the antiresonance field in a composite material are obtained.

The spatial distribution of magnetization oscillations of pure spin current induced in a thin layer of a non-magnetic conductor due to spin pumping is theoretically investigated. The influence of boundary conditions is studied. It is shown that if the oscillation frequency is lower than the spin relaxation frequency, the voltage at the surface of the conductor layer due to the inverse spin Hall effect is maximum when the layer thickness is close to the spin diffusion length.

The effect of thermomechanical treatment (TMechT), which includes annealing and cooling of the alloy under the external compressive load along the direction <001>, to magnetostriction of the Fe−18 at.%Ga alloy, has been investigated. Field dependencies of the longitudinal ${\lambda }_{100}^{\parallel }$ and transverse ${\lambda }_{100}^{\perp }$ magnetostriction are measured after TMechT with compressing stresses of 0–8 MPa. It is shown that as a result of TMechT already with small compressive stresses ~1 MPa, a significant change in the magnetostrictive behavior of the monocrystalline alloy occurs. The longitudinal component of magnetostriction ${\lambda }_{100}^{\parallel }$ increases, and the transverse ${\lambda }_{100}^{\perp }$ (by module) is reduced, while the complete magnetostrition ${\lambda }_{\text{s}}={\lambda }_{100}^{\parallel }-{\lambda }_{100}^{\perp }$ practically does not change. The maximum value of the saturation magnetostriction ${\lambda }_{100}^{\parallel }$ is observed after TMechT under stress of 2 MPa − about 280 ppm. After TMechT at higher stresses ${\lambda }_{100}^{\parallel }$ it is at the level of 200 ppm, and $\left|{\lambda }_{100}^{\perp }\right|$ decreases and reaches zero at 6 MPa. The observed effects of TMechO are explained by the directional ordering the Ga−Ga pairs in the BCC Fe−Ga alloy.

A model of the cluster structure of metal melts with a densely packed structure is considered. The minimum cluster size in the melt at the melting temperature of the crystal is determined. Using a 3-atomic chain of particles (in the Frenkel solid state model) interacting with a paired Morse potential, it is possible to obtain an estimate of the parameter determining the energy of interaction of particles in the chain. The value obtained is less than the value corresponding to the critical point of the order–disorder phase transition for inter-cluster boundaries in a 2-dimensional system. It is found that the change in the energy of a 3-dimensional system as a function of its temperature has an inflection point at a value corresponding to the structural disorder of the system: the critical point of the order–disorder phase transition for a two-dimensional layer of boundary nodes.

The atomic structure of monocrystalline samples of soft magnetic alloy Fe–9 at% Ga (A2-phase area) subjected to various thermal processing: 1 – quenching to water from paramagnetic state, 2 – annealing in a ferromagnetic state, 3 – thermomagnetic treatment (TMT) and 4 – thermomechanical treatment (TMechT), was studied by the method of X-ray diffraction. In the diffractograms of all samples, after different thermal treatments, diffuse peaks are observed, which are a contribution from small type of randomly located clusters of B2 type. A separate B2 cluster consists of a pair of BCC-cells centered by Ga atoms. The pair axis is parallel to one of the axes of easy magnetization <100>. It is shown that the width of diffuse peaks measured during scanning along the axis [001] decreases and, therefore, the average size of B2 clusters along this axis increases depending on the processing in the sequence of 1–2–3–4. The results obtained indicate a restructuring of short range order under the influence of TMT and TMechT.

The paper presents the developed model for predicting the behavior of a ferritic-martensitic steel during all creep stages. A modified θ-projection method is proposed as a solution. The main advantages of the method are abilities to model creep curves for a wide range of temperatures and stresses (which reduces the need for long-term run tests); to validate calculations by determining time to failure; to predict a steady-state creep rate. Despite the usefulness of the proposed approach, certain limitations are noted that result in modeling uncertainties. Higher accuracy and robustness can be achieved using a "mechanical equation of state equation" model of Rabotnov type.

The ferrite-bainite structure of X70 grade pipe steel was analyzed using transmission electron microscopy. The steel was produced using thermomechanical controlled processing technology and was used as part of a main gas pipeline for 40 years. It was shown, that during operation deformation aging processes develop in the steel structure, which significantly change the state of the fine structure of each of the phase components.