The work is devoted to the study of changes in the structural and physical properties of the precipitation-hardened CuCrZr alloy under the influence of low-temperature (77 K) quasihydroextrusion with various degrees of deformation at liquid nitrogen temperature with subsequent aging. Prior to quasihydroextrusion, commercial alloy samples were annealed and quenched from the premelting temperature to obtain a supersaturated solid solution of alloying elements in the copper matrix. After quasihydroextrusion, the microstructure, lattice constant, pole densities, tensile strength and yield strength, microhardness (in different cross-sections of the extrudate), and electrical conductivity of the CuCrZr alloy were studied depending on the degree of deformation by quasihydroextrusion. It is shown that the deformation degree determines the kinetics of decomposition of the supersaturated solid solution and its structure. As a result of extrusion, an anisotropic structure of the matrix and precipitates is formed, which also determines the anisotropy of material properties. Subsequent aging leads to a significant decrease in the anisotropy of properties. With an increase in the deformation degree during extrusion (before aging), a significant monotonous increase in physical and mechanical properties occurs. However, in the range of deformation degrees of 40–50%, an anomalous “jump” of all measured properties and structural parameters is observed. The study proposes a physical mechanism that explains the experimental results. The mechanism is based on the occurrence of two kinetically differently directed processes: dynamic aging and its inhibition due to an increase in the defectiveness of the material. The latter process manifests itself essentially at low temperatures. In general, low-temperature quasihydroextrusion makes it possible to obtain a complex of sufficiently high mechanical and electrical characteristics of the CuCrZr alloy at relatively low degrees of deformation for one extrusion cycle, which is facilitated by low deformation temperature.

Plastic deformation is one of the most important ways to improve metals and alloys' physical and mechanical properties. Many such treatment methods have been developed, but the opportunities provided by the temperature decreasing during deformation into the cryogenic region are being ignored. Despite the effectiveness of cryodeformation, work in this direction is practically not carried out today. There is reason to assume that the researchers are stopped by fears of the complexity of the implementation of such deformation treatment. There is a small number of published works dedicated to this direction, since, unfortunately, the following factors of cryodeformation applicability were not critically considered: the range of materials for which this type of plastic deformation provides the maximum effect, the complexity of equipment for such deformation. This paper discusses the problems of cryodeforming under all-around compression (barocryodeformation), methods, and features of its implementation. A new method of cryodeformation is proposed – cryo-upsetting under all-around compression, which, together with cryoquasihydroextrusion, significantly expands the possibilities of barocryodeformation of metals and alloys.

The new method of cryodeformation under all-around compression conditions is described. The impossibility of existing technologies to increase the efficiency of combined treatment of low-plasticity materials (in particular, the “upsetting-extrusion” method) by temperature treatment decreasing to the cryogenic region are considered. The technical possibility of such cryodeformation is discussed. The construction and operation principle of the developed device is described. The treatment efficiency of low-plasticity materials by this device on the example of technical magnesium and titanium nickelide alloy is shown. The need to clarify the formulations used to designate the methods of metals cryodeformation under conditions of all-round compression is discussed.

Subject and Purpose. The development and prototype making of a laser rangefinder operating in the 1.50…1.70 μm spectral region is reported. This wavelength region is attractive to both laser producers and laser users for, first of all, relative eye-safety of radiation. Methods and Methodology. The paraxial scheme of rangefinder construction is used, involving a software-controlled power supply of laser radiation with technical arrangements providing its adaptation to varying operating conditions. The alignment of the transceiver channels is provided with laser beam visualization methods. Results. A pulsed laser rangefinder operating at a 1.54 μm wavelength has been developed, a prototype has been made. The rangefinder essentially consists of the transmitting and receiving channels and the visual channel for targeting. The radiation source is a pulsed laser on ytterbium-erbium glass with semiconductor diode pumping and modulated Q-factor. The laser provides a 6 mJ power pulse of 25 ns duration and 5 mrad radiation divergence. A laser light spot of a required aperture is formed using a Galilean telescope system. For the photodetector of the reflected radiation, a pin-photodiode with a photosensitive area diagonal of 0.3 mm and a 2.5 ns time resolution is used. The echo signal processing module has been developed and performed, providing a high-precision registration of a time delay between the starting and reflected pulses. An effective method with the use of a charge-coupled device and an LCD monitor has been proposed and implemented for the alignment of all the three rangefinder channels. The rangefinder can operate in a single-pulse or repetitive-pulse mode with a probing pulse repetition rate of 1 Hz. Conclusion. A pulsed laser rangefinder operating in a relatively eye-safe spectrum region has been developed, a prototype has been made. The field tests have shown that the created rangefinder measures an object distance within 140…7 000 m with a measurement error no worse than 3 m.

Subject and Purpose. The problem of output beam matching with the waveguide transmission line often arises when using terahertz lasers. The special quasi-optical devices that are used to combat the problem lead to radiation losses and additional material costs. The aim of this work is to develop appropriate output mirrors for THz lasers so as to make the output laser beam match the transmission line of a given diameter. Methods and Methodology. As part of the experimental research into the action of the output mirror configuration on the parameters of THz laser radiation, gradient metal-film mirrors are made like a transparent substrate with a thin metal layer on it. The layer thickness varies over the substrate surface, forming therewith a transparency spot with a given change in the transmittance in the middle of the mirror. The properties of the gradient metal-film output mirrors are examined as applied to a gas-discharge HCN laser at a wavelength of 337 μm. Results. The gradient metal-film mirrors enable obtaining laser beams of a diameter equal to the inner diameter of the relevant transmission line and with a proper transverse energy distribution. The efficiency of the transmission of laser radiation energy into the waveguide line increases, and so does the performance of the laser installation. Another positive point is that the enhanced transparency in the middle of the mirror raises efficiency of the active substance energy utilization and conveys focusing properties to the flat mirror, which reduces diffraction losses. Conclusions. The employment of gradient metal-film output mirrors makes it possible to raise efficiency of laser installations. The features of metal-film mirrors suggest broad potentials for their application and make reasonable their further research.

Purpose: One-dimensional wire diffraction gratings, usually being mounted on ring frames, are often used in quasi-optical instruments under the construction of functional devices of different usage. Such gratings have been thoroughly studied theoretically and experimentally at the millimeter wavelengths, where they are most widely used and realized in various constructions of instruments and systems. However, a number of design and technological features of such gratings, connected with making the polarizing devices cannot be always taken into account in theoretical models that requires additional experiments. This problem is especially relevant in the terahertz range, where there is a lack of experimental data. This work aims at experimental studying the properties of one-dimensional wire gratings in the terahertz range at different angles of incidence of electromagnetic waves and for different adjustment conditions, as well as practical recommendations concerning the measurement technique and the creation of various polarizing devices. Design/Methodology/Approach: A measuring device has been developed and manufactured, in which a gas-discharge HCN laser (at the wavelength of 337 mm) is used as a radiation source. The study of one-dimensional wire gratings of two types was carried out: grating No. 1 (conductor diameter 70 μm, period 400 mm) and grating No. 2 (conductor diameter 50 μm, period 200 μm). The gratings were installed on a rotary stand. The stepper motor provided rotation within ±90°. Measurements were made automatically with a 0.35° step. The coefficient of laser radiation transmission through the grating was investigated depending on the angle of incidence and the adjustment accuracy. Findings: Analysis of the obtained data shows that the experimental results correlate with the theoretical data. Moreover, the experimental data more fully characterize the properties of the gratings, taking into account their design and technological features, which are very difficult to take into account theoretically. The resonance maxima in the experimental dependences of the transmitted power on the angle of incidence coincide with the calculated data that makes it possible to develop a number of new measuring techniques. Recommendations are given for improving the measurement accuracy and for the practical use of the obtained results. Conclusions: The obtained experimental results allow taking into account some additional features of the diffraction gratings, as well as improving the measurement technique. This is useful for the development of new devices in the terahertz range.

Recently, solid-state pumped semiconductor lasers have become increasingly widespread. Lasers of this type have several advantages over solid-state lasers with lamp pumping. First of all, this is high efficiency, long service life, small dimensions and weight. The use of semiconductor laser diodes for pumping solid-state active media imposes a number of rather stringent requirements on the power sources of laser diodes. The power source should provide rectangular current pulses with a flat top, a steep leading edge of the pulses and the absence of reverse current surges at the trailing edge.A pulsed power source for a diode pump system of a ytterbium-erbium laser was developed, manufactured and studied. In this source, the control unit provides functions for protecting the load in emergency conditions, controlling the charge of the storage capacitors to the required voltage and generating current pulses to power the laser diode line. The current is regulated by a field effect transistor operating in a linear mode. The load is included in the source circuit of the field-effect transistor, and the reference signal is generated by the DAC of the microcontroller. Such an approach made it possible to create a relatively simple, reliable and small-sized laser power source with a wide range of adjustment of the duration and amplitude of current pulses. This makes it possible to select the optimal operating mode depending on the characteristics of the active medium of the laser. Particular attention is paid to solving the problems of protecting expensive rulers of laser diodes from failure. The developed source can be used to pump other solid-state lasers with shorter lifetimes of the upper laser level than erbium.

Quasioptical THz wave receiver based on the widely accessible pyroelectric detector like PM-4 has been studied. The necessary components (modulator, receiver, preamplifier, synchronous detector, ADC module, and controller) are considered. The NEP of the pyroelectric detector was measured at 140GHz. Also, with the help of the Michelson interferometer, the wavelength measurements have been done. It is shown that the pyroelectric detector together with the mentioned components can be used to solve a number of problems in the THz frequency range, which do not require high sensitivity of the receiver.

The work is devoted to the design of a power supply unit with microcontroller control for a pulsed diode system for pumping an active medium of an erbium-ytterbium laser. The power supply provides a broad adjustment of the current pulse shape for flexible tuning of the laser operation mode. We used the scheme with MOSFET operating in the linear zone powered by a storage capacitor. In this case, the laser diode array connects to the source circuit of the MOSFET, which allows to power lasers in which the cathode of the laser diode array connects to the ground. The described in this paper power supply provides high parameters of the output pulse, a low level of electromagnetic interference, and has a system of protection against failure of laser diode arrays.

The results of studies aimed at the development and creation of an erbium-diode-laser laser with diode pumping and providing an output energy of several millijoules in pulses of 20-30 ns duration at a repetition rate of 0.5-1.0 hertz are presented.The interest around this laser is due to the fact that its radiation falls into the spectral region, which is relatively safe for vision. In this spectral region there is a transparency window in the earth's atmosphere. Thus, half-micron radiance can be used efficiently for location aims and rangefinder. This is facilitated by the presence of highly sensitive uncooled photo detectors. In addition, the spectral region of 1.5-1.6 μm matches with the region of maximum transparency of quartz optical fibers used in fiber-optic communication lines.The experimental sample of ytterbium-erbium laser emitting at a wave length of 1, 54 μm was designed and manufactured. Pumping of active element was done according to the transverse scheme by two laser diode rulers with a power of 100 W each, which has been put in line. The selected pump scheme provides a high excitation power and eliminates the occurrence of a temperature gradient in the active element. To increase the pumping efficiency, a cylindrical active laser element was placed in a sapphire cylinder, the outer surface of which had a reflective coating. During free generation regime, we implemented the optimization of laser characteristics, depending on the Q-factor of resonator and excitation conditions. To obtain a giant impulse, a passive Q-switch based on aluminum-magnesium spinel with cobalt was used in the work. In the Q-switched mode, single pulses with the energy of 6 mJ were obtained with a duration of less than 30 ns at a pulse repetition rate of one hertz.

This paper is devoted to the study of the effect of surface energy anisotropy on the tungsten surface relief modification under ion sputtering. In our experiments, the sputtering of textured polycrystalline tungsten with Ar ions resulted in a stepped surface relief formation. The surface after sputtering was analyzed using the electron backscatter diffraction and confocal laser scanning microscopy techniques. The formation of the stepped relief is explained by different surface energies of differently oriented grains (surface energy anisotropy). The surface energies of the three low-index W planes were calculated in the model of broken bonds. It is shown for the first time that the ratio of the sputtering depth of differently oriented grains of W is equal to the ratio of the differences of the surface energies of these grains. In that way, the ratio of the sputtering yields of differently oriented grains of tungsten can be quantified by knowing the surface energy, which depended on the reticular grain density and the number of broken bonds with nearest and next-nearest neighboring atoms on the surface using the broken bond model. It is shown that ion sputtering can be used as an instrument for studying the surface energy of solids.

This paper is devoted to experimental study of the influence of surface defects such as localized defects specific for polycrystalline materials, subjected to ion sputtering, on optical ellipsometry data. The study was performed using ferrite substrates with ferrite parallelepipeds of different size located in the center of the sample. A quasioptical multiangle terahertz ellipsometer that operates at 2.2 mm (0.14 THz) wavelength was used. Such a large wavelength makes it relatively easy to create structures with known geometric parameters on the surface under study. It is shown that ellipsometry is not sensitive to localized defects in the form of a parallelepiped if its size is comparable or smaller then the wavelength.

Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER and DEMO. One of the serious issues for PFCs is the high heat load during transient events and disruption in the reactor. Recrystallization and grain size growth in PFC materials are undesirable changes in the materials, since the microstructure developed after recrystallization exhibits a lower mechanical strength and an increased surface roughening. The current work was focused on careful investigation of the thermal grooving at grain boundaries (GB) in tungsten surface under recrystallization (W-rc). Topography of GB thermal grooves in W-rc is studied by atomic force microscopy (AFM). The peculiarities of its profile formation and the main factors which effect on the profile of GB grooving were determined. It is the purpose of this paper to point out these factors. The nature of GB grooving was determined.

Summarizing the experimental and theoretical trends observed on the changes in surface microstructure and topography resulting from surface energy anisotropy for the low-index crystal surfaces of the polycrystalline bcc tungsten under sputtering is done. A brief summary of the most closely related work is included. The experimental results have been discussed in the framework of the various theoretical methods. Emphasis was placed on the problems which are existing up to now. It is shown that the absence of a common trend in the ordering of the (100), (110), and (111) surface energies amongst the various theoretical models is a problem yet to be satisfactorily discussed. It is shown experimentally that for polycrystalline textured tungsten ( bcc metal), the order of the three low-index surface energies is gamma((111)) > gamma((100)) > gamma((110)).

The goal of the present paper is connected with spectral quasi-optical ellipsometer (SQOTE) creation, based on the hollow dielectric beamguide and beamguide components as a quasi-optical transmission line. Ultra-broadband quasi-optical transmittance line provides operation of the ellipsometer within 0.17-0.225 THz (1.2-1.8 mm) frequency range. The set of elements of the transmittance line, which require matching with the generator, was determined. The principle and details of SQOTE measurements were described and its accuracy was estimated. Experimental testing of the ellipsometer was carried out by comparing dielectric constants of a set of materials measured by the setup with reference data and with the results of independent reflectometry measurements.

Экспериментально изучена модификация структуры

In the paper influence of thermal treatment and equal-channel angular pressing (ECAP) on properties of high-temperature Cu-Cr-Zr composite is studied. It is shown, that proper combination of these two treatments leads to increase of the alloy microhardness while preserving high electroconductivity. It is proved experimentally, that structure formation of Cr-rich precipitates is not connected with the size of the matrix structural elements which is close to the size of the precipitates. High ECAP-induced anisotropy of both structure and spatial arrangement of Cr-rich fibers along and across the sample axis, and of the composite microhardness is revealed. It is shown, that ECAP results in anisotropic strengthening of the composite due to anisotropic distribution of Cr-rich precipitates. Conductivity remains rather high and isotropic since it is determined by the isotropic matrix properties.

The effect of various kinds of severe plastic deformation (equal-channel angular pressing and quasi-hydrostatic extrusion at 77 and 300 K) on the structural formation of precipitation-strengthened CuCrZr alloy has been studied. A combination of experimental methods has been used. Sputtering by deuterium ions was used as the tool for the layer-by-layer study of the alloy structure. The difference between the sputtering yields of the matrix (copper) and precipitates (Cr and Zr) allowed us to visualize the alloy structure to a total depth of 0.5−1 μm. The effect of severe plastic deformation on the precipitate distribution is considered. It has been shown that the main peculiarity of the microstructure is related to the high density of precipitates enriched in chromium, which completely determine the surface roughness. Their distribution is not related to the grain size. The combination of equal-channel angular pressing and quasi-hydrostatic extrusion was shown to lead to the increase in the microhardness of the CuCrZr alloy to 2300 MPa in the case of low-temperature quasi-hydrostatic extrusion (at 77 K) and to the retained high conductivity. It has been proved that the high anisotropy of precipitate shape, microhardness, and sputtering yield of the CuCrZr alloy is determined by equal-channel angular pressing.