卷 117, 编号 9 (2016)

The causes of changes in the magnetic properties of an amorphous Co–Ni–Fe–Cr–Si–B alloy obtained by melt spinning in the form of a thin ribbon subjected to heat treatment and subsequent action of temperatures corresponding to various conditions of its exploitation have been analyzed. We have established the regimes of heat treatment that provide for the highest values of the maximum magnetic permeability of the alloy and the shielding factor of a magnetic shield made from the alloy. We have analyzed changes in the magnetic properties, shielding properties, and total magnetization distribution in an alloy ribbon at a temperature well below the crystallization temperature. We have found the temperature ranges that determine the practical application of this alloy.

The influence of water vapors and plastic deformation on the structure and electrophysical properties of YBa₂Cu₃O_6.9 (123) has been studied. It has been established that, at T = 200°C, the introduction of water into the structure of YBa₂Cu₃O_6.9 leads to its transition into a defect tetragonal phase of the 124 type as a result of the formation of planar stacking faults. After annealing at T = 930°C, these defects are partially retained and are efficient centers of pinning in the magnetic fields applied perpendicularly to the c axis, which makes it possible to increase (by an order of magnitude) the critical current density in the high-textured ceramics at 77 K in the external magnetic field of 5–10 T. The plastic deformation of the hydrated ceramics favors the reverse transition of the arising 124 phase to the 123 phase at T = 930°C and is accompanied by a recrystallization of the material, which leads to the appearance of a texture and an increase the critical current density.

The method of growth from a melt solution was used to obtain iron-alloyed (0.08 at %) Al–Cu–Co single crystals with a decagonal symmetry. The temperature dependences of the electrical resistivity in magnetic fields of 0–18 T were measured using samples oriented in the periodic direction (ρ_p(T)) and in the quasi-periodic plane (ρ_q(T)). A strong anisotropy of the resistivity was observed; the ρ_p(T) curve is linear, whereas the ρ_q(T) curve is approximated well by a second-order polynomial. A strong anisotropy of the magnetoresistance was also observed; a positive magnetoresistance Δρ/ρ ~ 10^–3 for the current flowing in the quasiperiodic plane; and a weak (close to zero) negative magnetoresistance for the current flowing along the periodic direction.

The structure of compacted specimens produced using the rapid laser melting of ultradispersed Fe–50 wt % Cu powders has been studied. The original powder was produced via the mechanical milling of iron and copper powders in a planetary-type ball mill. It has been found that the structure of the compacted specimens produced using rapid laser melting exhibits signs of the initial stages of separation in supercooled liquid. It has been shown using X-ray diffraction analysis as well as scanning and transmission electron microscopy that the final structure contains a supersaturated (Fe; Cu) solid solution formed from the high-speed movement of the solidification front and the nonequilibrium capture of copper by the moving front.

The fine structure of pearlite in alloys with the structure of gray cast iron that contain 1.6 and 10.8 wt% copper has been studied using transmission electron microscopy. Peculiarities of the formation of the nanosized particles of the ε-phase in ferrite lamellae of the pearlite have been determined and their influence on the character of the dislocation structure in the ferrite constituent of the pearlite has been demonstrated. It has been found that the Kurdyumov–Sachs orientation relationship is established between the particles of the ε and α phases. In the investigated cast irons, the formation of nanosized ε-copper particles results in the growth of pearlite hardness by 35 HV and 84 HV, respectively.

The material of a shell structure subjected to 20-year use under ambient conditions has been studied. The structure and mechanical characteristics of a strain-hardened AMg6 alloy, as well as the effect of subsequent holdings of this alloy for 10–3000 h at temperatures of 50, 70, 80, 100, 130, 150, 180, and 220°C, on changes in its dislocation structure and mechanical characteristics have been investigated. It has been shown that, in the structures under study, the AMg6 alloy has a cellular structure with a high density of dislocations and the ultimate strength σ_u = 445.5 ± 2.5 MPa, the proof stress σ_0.2 = 326.5 ± 3.5 MPa, and the relative elongation δ = 11.7 ± 0.5%. Polygonization in the alloy occurs at a temperature of 220°C and the initial stage of the recovery process corresponds to a temperature range of 50–100°С in which the softening process can be divided into two stages, i.e., stage (1) of active softening due to the interaction of point defects with each other and stage (2) of the stabilization of the characteristics of the alloy.

The influence of correlation effects due to thermodynamic interaction of alloy components on segregation processes upon radiation treatment has been analyzed. The analysis has been performed for 53 metallic solid solutions. It has been shown that the short-range order in alloys causes a redistribution of flows of radiation defects and changes the mechanism of their annihilation, which in a certain temperature range is responsible for the high resistance of alloys to radiation swelling. The presence of two maxima in the curve of the temperature dependence of swelling for austenitic nickel–chromium alloys is associated with the existence therein of different types of short-range order at different temperatures.

Structure and physicomechanical properties of Cu–Pd alloys that contain 0.5–5.9 at % Pd have been studied. It has been shown that, in all alloys, a solid solution is formed; the lattice parameter of the fcc lattice and the electrical resistivity of the alloys grow linearly with an increase in the content of palladium. It has also been revealed that the introduction of palladium leads to an increase in the recrystallization temperature and to an increase in the strength properties. The assumption on the formation of an atomic short-range order in the quenched Cu–4.6 at %Pd and Cu–5.9 at %Pd alloys has been made.

This work was performed to study the behavior of 45Ti–45Ni–10Nb and 43Ti–46Ni–8Nb–3Zr (at %) shape-memory alloys (SMAs) under the effect of severe dynamic deformation to use the obtained results to develop technologies based on SMAs. Cast alloys were used for the tests. The elemental and phase compositions of the alloys in the initial state, as well as the phase composition, kinetics, and temperatures of phase transformations after heat treatment (annealing in a vacuum at 850°C for 4 h, furnace cooling) have been determined. The mechanical and thermomechanical characteristics of these alloys before and after shock-wave loading have been determined.