卷 117, 编号 12 (2016)

Spin valves with a synthetic antiferromagnet have been prepared by magnetron sputtering. Regularities of the formation of single- and two-phase spin-flop states in the synthetic antiferromagnet have been studied using magnetoresistance measurements and imaging the magnetic structure. A thermomagnetic treatment of spin valve in a field that corresponds to the single-phase spin-flop state of synthetic antiferromagnet was shown to allow us to obtain a magnetically sensitive material characterized by hysteresis-free field dependence of the magnetoresistance.

Methods of nuclear magnetic resonance and X-ray reflectometry have been used to investigate the state of interfaces in Co/Cu superlattices with different thicknesses of the nonmagnetic layers of Cu. It has been shown that, with an increase in the thicknesses of Cu layers, the perfection of the structure of the interfaces deteriorates.

The deformation-intensified atomic Mn-related separation of the bcc solid solution has been found in Fe_100–xMn_x alloys (x = 4.5–9.9) subjected to ball milling using Mössbauer spectroscopy. In the near surrounding of iron atoms, the atomic separation is similar to that observed upon the annealing of the alloys in a temperature range of 400–500°С. It has been found that the deformation-intensified atomic separation leads to the stabilization of the bcc phase with regard to the α → γ transformation, as well as to the expansion of the field of the existence of the bcc phase during heating.

Based on the CALPHAD method, a thermodynamic description of the Fe–M–V–NB–Ti–C–N system (where M is Al, Cr, Mn, Ni, or Si) has been constructed and, using this description, the solubilities of carbonitrides in austenite for low-alloy low-carbon steels with V, Nb, and Ti have been calculated using 10G2FB steel as an example. The influence of the alloy composition and temperature on the composition and amount of carbonitride phases and on the concentration of these elements in the solid solution has been analyzed.

The microstructure, phase composition, and mechanical characteristics of the structural constituents of an Al–Cu–Mg–Si alloy in which the liquation of grain boundaries occurred during heat treatment have been studied. Bands of the (Al + Al₁₅(Fe, Mn)₃Si₂) eutectics have been observed at the grain boundaries. An algorithm for calculating the additional pressure, which results from mechanical impact on the metal containing these bands has been described.

Methods of transmission and scanning electron microscopy and chemical microanalysis, electron diffraction, and X-ray diffraction were used to study the structure and the chemical and phase composition of ribbons of the four-component quasi-binary alloy Ni₄₅Ti₃₂Hf₁₈Cu₅. The influence of the synthesis regimes and subsequent heat treatment of the alloy on the formation of the amorphized state and ultrafine-grained structure has been determined. The critical temperatures of the devitrification and of the _B2 ↔ _B19' thermoelastic martensitic transformation have been established based on the data of the temperature dependences of the electrical resistivity. The lattice parameters of the _B2 and _B19' phases and the (Ti,Hf)₂Ni phase have been determined by X-ray diffraction. The mechanical properties of the alloy were determined in tensile tests, and the shape-memory effects in the ribbons of the alloy were measured using bending tests.

Methods of metallography, scanning electron, and transmission electron microscopies were used to study the structure of two pipe steels (without vanadium and with 0.03% vanadium) subjected to γ → α isothermal transformation at temperatures of 400–600°C (initial structure) and tempering at 600–650°C. It has been found that the addition of 0.03% vanadium intensifies the process of the precipitation of ferrite and contributes to the formation of a granular structure. It has been shown that, in high-strength pipe steels with 0.03% vanadium, which have bainitic granular-type structures, the effect of the precipitation strengthening is effected upon subsequent high-temperature tempering at 600–630°; the addition of vanadium leads to an increase in the hardness by 16 HV. In the presence of bainite of the lath type in the initial structure, the subsequent tempering leads to a softening associated with the processes of the recovery, polygonization, and initial stages of recrystallization in situ, which develops at temperatures above 640°C. It has been found that the hardness of the steel without vanadium upon additional tempering decreases regardless of the morphology of structural constituents in the initial structure.

The dependence of the plasticity of polycrystalline molybdenum on the strain rate has been studied after deformation performed under pressure and at an ambient temperature of 293 K. The samples were deformed in tensile tests. The strain rate of tensile deformation and the pressure in each experiment are constant. The range of the strain rate is 8.3 × 10⁻⁷ to 8.3 m/s and the pressure is 0.1–500 MPa. At a pressure of ambient atmosphere, molybdenum at a strain rate less than 200 s^–1 in value (10^2.3 s^–1) fractures in a brittle manner with zero residual strain. The brittle fracture of the working part of a cylindrical sample occurs simultaneously in several places. The molybdenum plasticity decreases in the range of low strain rates regardless of the pressure and, on the contrary, plasticity under pressure increases in the range of high strain rates. The strain rate of tensile deformation at which the dependence of the plasticity on the strain rate under pressure changes is 8.3 × 10^–4 m/s (a strain rate of 0.25 s^–1). The high plasticity of molybdenum after deformation under pressure is observed at high strain rates.