Vol 83, No 10 (2019)

State switching processes play an important role in the control of nanodevices and properties of many quasi-one-dimensional objects in physics, chemistry and biology. The paper considers the propagation of the state switching front from the sample boundary with the absorption of the emerging domains of the new phase at active centers in the bulk. The corresponding statistical-kinetic problem is solved with the calculation of the generating function of the distribution of domain wall positions, by means of which the average values of the “relay” runs are calculated.

The growth of grains in nano- and submicrocrystalline nickel produced via equal channel angular pressing is investigated under conditions of non-isothermal annealing using differential scanning calorimetry and transmission electron microscopy. Both types of the material exhibit abnormal grain growth that can be described in terms of the Johnson–Mehl–Avrami formalism.

The effect of combined deformation on changes in the plastic and strength characteristics of silicon is investigated. A notable increase in plasticity upon combined deformation compared to traditional hot deformation is revealed. It is shown that the microhardness of silicon is reduced as plastic deformation increases. The mobility of dislocations has an appreciable effect on the strength characteristics of silicon single crystals. Surface microstructures of the deformed samples are studied. A possible explanation for the observed effects is given.

The sintering of Fe–Ni austenitic alloy at 4.5 GPa, 900°C and 8 GPa, 800°C with mechanically milled fullerene C₆₀, 1.7 at % results in the dissolution of carbon in the FCC lattice of the alloy, and the formation of carbides and isolated regions containing fine powder mixes of the alloy and carbon phase. The microhardness of these regions is twice as high as that of the alloy.

The possibility of using a ball mill to obtain an amorphous state in bulk amorphous Fe_61.4Ni_3.6Cr_3.2Si_2.4Nb_7.8Mn_3.6B₁₈ alloy is studied. The presence of a metastable phase in the initial reagents allows the rate of amorphization to be notably accelerated with an almost full transformation to the amorphous state. Compared to a quench-hardened tape, however, the content of the amorphous state obtained via mechanical milling is distinguished by a reduced content of boron and therefore a lower temperature of crystallization.

The local curvature and torsion (χ) of the crystal lattice formed during the deformation of polycrystalline FCC solid solutions is studied via transmission electron microscopy (TEM). Polycrystalline alloys of Cu and Al (Al contents of 0.5 and 14 at %) with mean grain sizes of 10 to 240 µm are considered. It is established that the sources of curvature and torsion are boundary intersections, grain boundaries, and misoriented dislocation and disclination substructures that form during deformation of the alloys. The greatest curvature and torsion of the crystal lattice are due to grain boundaries and boundary intersections. The effect of grain size has on the value of χ is determined.

Features of surface etching are investigated along with the decoration of shear bands of Co–Fe–Cr–Si–B amorphous alloys obtained via melt quenching. The nature of the observed etching effects is discussed on the basis of data from Auger spectroscopy and predicted coefficients of diffusion.

Electroerosion-resistant CuO–Ag system coatings are obtained via electric explosive spraying and subsequent electron beam processing for the first time. The coatings are a structurally homogeneous composite material consisting of a silver matrix with copper oxide inclusions. The CuO–Ag system coatings have a wear resistance more than 300% greater than that of copper. The basis of the structural formation of the CuO–Ag system electric-explosive coating is the dynamic rotation of sprayed particles that form a hierarchically organized vortex structure in both the coating and in the upper layers of the substrate, including their interface.

The structural phase states and mechanical properties of hypoeutectic silumin subjected to electron beam treatment with energy density of 10–35 J cm⁻² are studied according to modern physical materials science. Treating silumin with an electron beam that has an energy density of 25 J cm⁻² leads to the formation of a cellular structure in a layer that is up to 40 μm thick. The increase in the hardness of the surface layer of silumin is apparently due to the formation of a high-speed cellular crystallization structure of submicron size with nanoscale layers of the second phase distributed along the cell boundaries.

Cubic magnetic nanoparticles with average sizes of 16.1 ± 2.2, 22.3 ± 3.5, and 37.4 ± 5.2 nm are obtained by a variety of means. The magnetic characteristics of these nanoparticles are studied as well. The samples are probed via X-ray diffraction to establish structural features, and the specific absorption rate (SAR) is analyzed as a function of the frequency and induction of an alternating magnetic field.

A review is presented of using nonlinear coherent spectroscopy to monitor the state of colloidal solutions of nanoparticles (Ti, Ni, and Ag) employed to improve the performance of supercapacitors, and to determine the effect nanosilver has on the hepatitis C virus. Examples of the spectra of a colloidal silver solution in two phase states (nanosilver and silver in the finely dispersed phase) are given.

Radiation sterilization of bone implants can lead to substantial morphological changes in them and the degradation of their physical and mechanical properties, depending on the magnitude of the absorption dose. The structure of bone samples changes starting at doses of 15 kGy. Raising the dose to 25–50 kGy affects the mechanical characteristics and osteinductive properties of bone implants. Data on the morphological and mechanical changes, and their analysis and systematization, are the scientific basis for developing modern requirements and practical recommendations for further improvement of the radiation technologies for the sterilization of biological tissues.