Diffraction Mode Research Articles

Symmetry mode analysis of distorted polar/nonpolar structures in A -site ordered SmBaMn2O6 perovskite

We present a comprehensive structural study of the charge-orbital ordering and magnetic phase transitions observed in the $A$-site ordered $\mathrm{SmBa}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$ perovskite combining synchrotron radiation x-ray powder diffraction and symmetry-adapted modes analysis. In $\mathrm{SmBa}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$, successive phase transitions in charge, spin, and lattice degrees of freedom take place with decreasing temperature at ${T}_{\mathrm{CO}1}\ensuremath{\approx}380\phantom{\rule{0.16em}{0ex}}\mathrm{K}, {T}_{\mathrm{CO}2}\ensuremath{\approx}190\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, and ${T}_{\mathrm{N}}\ensuremath{\approx}250\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The main difference between the two charge-ordered phases concerns the stacking sequence along the $c$ axis, which is double for the high temperature charge-ordered phase and has led to controversy in the literature. We show that both charge-ordered phases are pseudosymmetric with respect to the ideal undistorted tetragonal structure of $A$-site ordered $R\mathrm{Ba}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$ perovskites and lead to two nonequivalent Mn sites. However, the charge segregation stabilizes at about $0.35{e}^{\ensuremath{-}}$ in the low temperature charge-ordered phase, clearly below the nominal separation of one charge unit between ${\mathrm{Mn}}^{3+}$ and ${\mathrm{Mn}}^{4+}$ and undergoes a prominent increase in the high temperature charge-ordered phase when warming above $\ensuremath{\approx}250\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The two Mn sites are anisotropic in both charge-ordered phases but the analysis of the active modes discloses that only the low temperature charge-ordered phase displays a Jahn-Teller-like distortion for one of the Mn sites. In addition, this low temperature charge-ordered phase has polar symmetry compatible with ferroelectricity along the $a$ axis.

Nano-sheets of two-dimensional polymers with dinuclear (arene)ruthenium nodes, synthesised at a liquid/liquid interface

We developed a new class of mono- or few-layered two-dimensional polymers based on dinuclear (arene)ruthenium nodes, obtained by combining the imine condensation with an interfacial chemistry process, and use a modified Langmuir–Schaefer method to transfer them onto solid surfaces. Robust nano-sheets of two-dimensional polymers including dinuclear complexes of heavy ruthenium atoms as nodes were synthesised. These nano-sheets, whose thickness is of a few tens of nanometers, were suspended onto solid porous membranes. Then, they were thoroughly characterised with a combination of local probes, including Raman spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy in imaging and diffraction mode.

Light absorption suppression in cholesteric liquid crystals with magneto-optical activity

We investigated the peculiarities of absorption of cholesteric liquid crystals (CLCs) with magneto-optical activity, and also the changes in the spectra of intensity, ellipticity, and azimuth of the total wave excited in the medium in the diffraction mode from the parameter z/p, where p is the pitch of the helix and z is the coordinate of the axis directed along the axis of the medium. We have shown that, if in the absence of an external magnetic field the effects of anomalously weak (full suppression of absorption) and anomalously strong absorptions have a pronounced expression, then in the presence of an external magnetic field at large values ​​of the magneto-optical activity parameter, they practically do not appear, or best-case scenario has a weak manifestation. It is shown that the weak manifestation of anomalously weak absorption in photonic band gap is due to of appearance of ellipticity at total wave excited in a medium in the presence of magneto-optical activity. As it is shown at large values of the magneto-optical activity parameter, not only the real parts of the wave vectors of the eigenmodes are shifted, but also their imaginary parts, causing new absorption features.

Cooling Metals via Gap Plasmon Resonance.

We report highly emissive and radiatively cooled metallic surfaces that sustain multiple and high-amplitude gap plasmon cavity modes within the principal thermal radiation spectrum at room temperature (i.e., 8-13 μm). A square-lattice array of Cu/ZnS/Cu gap plasmon cavities with five different widths was designed to avoid the near-field coupling between adjacent cavities and the anticrossing of a cavity mode and the first diffraction mode. The gap plasmon cavities fabricated on a Si substrate exhibited an effective emissivity of >0.62, up to an incidence of 60°. Outdoor solar heating experiments showed that the Cu/ZnS/Cu multicavity array lowered the Si substrate temperature by 4 °C at a maximum solar irradiance of 800 W/m2, which is equivalent to a near-one-sun intensity, relative to a planar Cu/ZnS/Cu multilayer. Such mid-infrared spectrum management of metals enables heat dissipation via radiation, which will be further utilized for designing electrodes that cool optoelectronic devices with the same metal/dielectric/metal configuration.

Growth and Characterizations of Rhenium Disulfide (ReS2) Single Crystals

Rhenium disulfide (ReS2) single crystals are grown by chemical vapor transport technique. Powder X‐ray diffraction analysis of the single crystals shows them to possess ReS2 phase with triclinic unit cell structure. Energy dispersive analysis of X‐rays shows the crystals to be slightly rich in sulfur and deficient in rhenium. The optical bandgap obtained of the as‐grown single crystals is 1.35 eV. The surface morphology study done by scanning electron microscopy shows that the crystal surface to be flat with layer edges, such observation states that the growth mechanism of crystal have happened by mechanism of sheet spreading. The transmission and diffraction mode electron microscopy shows the single crystals to be layered and crystalline, respectively. The Raman peaks are well assigned to the ReS2. Thermogravimetric and differential thermogravimetric analysis shows the single crystals to disintegrate by two steps. The differential thermal analysis shows that the ReS2 possesses initial endothermic followed by exothermic nature for fast heating rates. In case of a slow heating rate of 10 K min−1, other than endothermic followed by exothermic, the end temperature range shows endothermic nature. The kinetic parameters determined by Kissinger relation shows the single‐crystal samples to disintegrate at a higher temperature range.

Microfabrication and Surface Functionalization of Soda Lime Glass through Direct Laser Interference Patterning.

All-purpose glasses are common in many established and emerging industries, such as microelectronics, photovoltaics, optical components, and biomedical devices due to their outstanding combination of mechanical, optical, thermal, and chemical properties. Surface functionalization through nano/micropatterning can further enhance glasses’ surface properties, expanding their applicability into new fields. Although laser structuring methods have been successfully employed on many absorbing materials, the processability of transparent materials with visible laser radiation has not been intensively studied, especially for producing structures smaller than 10 µm. Here, interference-based optical setups are used to directly pattern soda lime substrates through non-lineal absorption with ps-pulsed laser radiation in the visible spectrum. Line- and dot-like patterns are fabricated with spatial periods between 2.3 and 9.0 µm and aspect ratios up to 0.29. Furthermore, laser-induced periodic surface structures (LIPSS) with a feature size of approximately 300 nm are visible within these microstructures. The textured surfaces show significantly modified properties. Namely, the treated surfaces have an increased hydrophilic behavior, even reaching a super-hydrophilic state for some cases. In addition, the micropatterns act as relief diffraction gratings, which split incident light into diffraction modes. The process parameters were optimized to produce high-quality textures with super-hydrophilic properties and diffraction efficiencies above 30%.

Frequency-selective modulation of reflected wave fronts using a four-mode coding acoustic metasurface

Designing a multiplexing metasurface to exhibit diverse functionalities has been a trend in electromagnetics, acoustics, and mechanics. Here, we report a simple method to design the 2-bit coding acoustic metasurface by combining the Helmholtz resonator-like structures. Each meta-atom has four coding modes to independently modulate the wave fronts at two different frequencies. The equivalent circuit principle and decoupling effect are theoretically and numerically analyzed to clarify the underlying physical mechanism of our design. We filter and suppress the redundant diffraction beams to realize perfect negative reflection by controlling the number of outgoing diffraction modes. Considering the impact of loss, we simulate the scattered pressure and directivity of far field radiation for oblique illumination at two predesigned frequencies, the results of which show good agreement with the predicted ones. Our work may have potential in the design of multiplexing, frequency-selective, and programmable acoustic devices.

Surface Boriding and Titanization Stainless Steel by Integrated Processes

The phase and element composition, defect sub-structure in the surface layer of stainless high-chromium steel 12Cr18Ni10Ti (0.12% C, 1.8% Cr, 10% Ni, 1% Ti) alloyed in the electric explosion have been investigated in an X-ray analysis and with the help of optical, scanning and transmission electron microscopy in the diffraction mode. Titanium and boron have been selected as alloying elements. Once a steel surface modified via the electrical explosion alloying is irradiated by an intensive pulsed electron beam, a multi-phase sub-micro nano-crystalline surface layer (up to 60 μm) with no micro-pores and micro-craters is produced. The research has demonstrated two-element compounds only form in the modified layer of steel. The microhardness of a modified layer is related to a part of titanium borides in the surface of steel, being more than 18 times higher after the electrical explosion alloying than in as delivered state. As a result of the subsequent irradiation by an electron beam, a surface layer is formed in the steel alloyed via the electrical explosion; the microhardness and wear resistance of this layer are seven and nine times, respectively, higher than these parameters in as delivered state.

Формирование интерметаллида Cu-=SUB=-6-=/SUB=-Sn-=SUB=-5-=/SUB=- в тонких пленках Cu/Sn

The study of the formation of the Cu6Sn5 intermetallic compound in Sn(55nm)/Cu(30nm) thin bilayer films was carried out directly in the column of a transmission electron microscope (electron diffraction mode) by heating the film sample from room temperature to 300 °C and recording the electron diffraction patterns. The thin films formed as a result of a solid state reaction were monophase and consisted of the η-Cu6Sn5 hexagonal phase. The temperature range for the formation of the η-Cu6Sn5 phase was determined. The estimate of the effective interdiffusion coefficient of the reaction suggests that the main mechanism for the formation of the Cu6Sn5 intermetallic is diffusion along the grain boundaries and dislocations.

Акустооптическое управление энергетическим 2D-профилем лазерного луча

The acousto-optic control of the energy profile of laser radiation is considered. A highly efficient multibeam Bragg diffraction mode with a combination of beams close in angular space, forming an averaged pattern in the form of a single beam, is used. In this case, the two-dimensional intensity profile is realized as a product of two independent one-dimensional profiles. On the basis of a polarization-independent two-coordinate acousto-optic deflector, several profiles (including a close to uniform one) were experimentally obtained with a total efficiency of no less than 85% and a profile change time of about ten microseconds. This method can be used in systems for processing materials with powerful lasers.

Dual-Polarized All-Metallic Metagratings For Perfect Anomalous Reflection

We theoretically formulate and experimentally demonstrate the design of metagratings (MGs) composed of periodic rectangular grooves in a metallic medium, intended for perfect anomalous reflection. Using mode matching, a semianalytical scheme for analysis and synthesis of such MGs, containing multiple, arbitrarily arranged, grooves per period, is derived. Following the typical MG design approach, we use this formalism to identify the relevant Floquet-Bloch (FB) modes and conveniently formulate constraints for suppression of spurious scattering, directly tying the structure's geometrical degrees of freedom (DOFs) to the desired functionality. Solving this set of constraints, in turn, yields a detailed fabrication-ready MG design, without any full-wave optimization. Besides providing means to realize highly-efficient beam deflection with all-metallic formations, we show that the rectangular (two-dimensional) groove configuration enables \emph{simultaneous} manipulation of both transverse electric (TE) and transverse magnetic (TM) polarized fields, unavailable to date with common, printed-circuit-board-based, microwave MGs. In addition, we highlight a physical limitation on the TE-polarization performance, preventing the ability to achieve perfect anomalous reflection in any desired angle. These capabilities are verified using three MG prototypes, produced with standard computer numerical control (CNC) machines, demonstrating both single- and dual-polarized control of multiple diffraction modes. These results enable the use of MGs for a broader range of applications, where dual-polarized control is required, or all-metallic devices are preferable (e.g., spaceborne systems or at high operating frequencies).

Strain determination in heterostructures by TEM in selected area electron diffraction mode

The technique for determination of strain and elemental composition distribution across the graded layer in heterostructures by means of selected area electron diffraction in transmission electron microscope (TEM) is proposed. The approach accounts for the modification in the residual elastic strain due to sample thinning during TEM specimen preparation. The technique is approved using In0,7Ga0,3As/InxAl1-xAs/GaAs(001) and Al0,75Ga0,25N/AlN/Al2O3 heterostructures, and the results are in a good agreement with those obtained by alternative ways.

Residual stresses and tribomechanical behaviour of TiAlN and TiAlCN monolayer and multilayer coatings by DCMS and HiPIMS

The deposition of ternary nitrides with the incorporation of carbon atoms into its structure has demonstrated to be a promising approach in the pursuit of wear-resistant and self-lubricating coatings. Firstly, both TiAlN and TiAlCN monolayers were deposited using direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) onto quenched and tempered AISI H11 tool steel to be used as references. Acetylene was used as a carbon precursor, producing DCMS and HiPIMS TiAlCN coatings with 9.0 and 21.7 at.% C, respectively.Subsequently, TiAlN/TiAlCN multilayers of various designs were also developed as follows: 5×[10/500], 5×[50/500] and 5×[100/500] nm. Residual stresses of the coating systems were determined by X-ray radiation utilising an ETA-diffractometer with a Cu-Kα radiation source applying the sin2ψ method. Additionally, residual stresses depth gradients of the substrate before and after the deposition of the coatings were determined in a LEDDI 8-circle diffractometer equipped with a W-X-ray tube and operated in the energy-dispersive mode of diffraction. Great reduction of the compressive residual stresses in the coatings was observed after the introduction of carbon into the TiAlN coating structure, shifting from −1047 ± 149 to −307 ± 211 MPa for the DCMS and from −7035 ± 1361 to +989 ± 187 MPa for the HiPIMS coatings. In the multilayer coatings, compressive residual stresses increase along with the increment of the TiAlN interlayer. Additionally, residual stresses of the substrate in the near-surface are dragged from low compressive stresses (−218 ± 61) to tensile stresses in the range of 1000 to 2000 MPa for all the DCMS/substrate systems, a behaviour only presented in HiPIMS by the TiAlN monolayer. Wear coefficients of all the evaluated HiPIMS systems are notoriously lower than their DCMS counterparts. Compared to TiAlN, TiAlCN HiPIMS presented a lower coefficient of friction but a higher wear coefficient, which in turn was not reduced by the introduction of the multilayer systems. Finally, Scratch test and Rockwell C adhesion tests have shown higher adhesion of DCMS coatings than HiPIMS coatings, and a detriment of the monolayers adhesion by the implementation of TiAlN/TiAlCN multilayer systems. The understanding of the residual stresses, both in the coating and in the substrate, and the way they affect the tribomechanical performance of the system coating/substrate continues to be of great importance, especially for coatings deposited by new technologies such as HiPIMS and self-lubricating coatings.

Wavelength Tunable OAM Mode Converters Based on Chiral Long-Period Gratings

We have demonstrated direct generation of high-order orbital angular momentum (OAM) modes by chiral long-period gratings (CLPGs) written in a few mode fiber (FMF) via a CO2 laser. The high-order core modes (LP11, LP21, and LP31 modes) were realized by the CLPGs through high order diffraction modes with efficiencies of more than 99.69%. The -1st, −2nd, and −3rd order OAM modes can be generated directly by the CLPGs with various grating periods. The proposed method opens a new path to implement all fiber high-order OAM mode generation. The OAM mode converters can be adopted as wavelength tunable mode converters by adjusting twist rate of the CLPGs, which could be widely used in optical communication and fiber sensing system based on FMFs.

Conditions for surface lattice resonances and enhancement of second harmonic generation based on split-ring resonators

In this paper, we theoretically study the condition for the strong coupling between magnetic resonance mode of the two-dimensional periodically arranged gold split-ring resonators and the diffraction mode of the periodic array and its influence on the second harmonic generation efficiency. By controlling the size of the period of the array structure in the <i>x</i>-axis and <i>y</i>-axis, the diffraction mode is excited near the magnetic resonance provided by the gold split-ring resonator, solely in one of the directions. In both cases, the diffraction mode and the magnetic resonance coincide in the linear resonance spectrum, but by analyzing the electric field distribution at the position of the diffraction mode, it can be found that when <inline-formula><tex-math id="M152">\begin{document}${a_x}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M152.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M152.png"/></alternatives></inline-formula> is much larger than <inline-formula><tex-math id="M153">\begin{document}${a_y}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M153.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M153.png"/></alternatives></inline-formula>, the electric field direction of the diffraction mode is perpendicular to the polarization direction of the incident light, and no strong coupling occurs. Therefore, the dilution effect is dominant, and the second harmonic intensity gradually decreases with the increase of the period. When <inline-formula><tex-math id="M154">\begin{document}${a_y}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M154.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M154.png"/></alternatives></inline-formula> is much larger than<inline-formula><tex-math id="M155">\begin{document}${a_x}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M155.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20201424_M155.png"/></alternatives></inline-formula>, the electric field direction of the diffraction mode is the same as the polarization direction of the incident light. At this time, the diffraction mode and the magnetic resonance mode are strongly coupled. As the period increases, the second harmonic intensity first increases and then decreases. The increase is due to the dominant mode coupling and the decrease is due to the dominant dilution effect. When the number density of split-ring resonators is reduced to about 1/4 of the original one, the second harmonic intensity can be increased by more than twice. From this, we find that the strong coupling between diffraction mode and magnetic resonance can occur when the electric field direction of the diffraction mode is consistent with the polarization direction of incident light, thus generating the surface lattice resonance to achieve near-field enhancement. In short, the rectangular periodic structure is used to distinguish the field enhancement effects in different directions, and the second harmonic enhancement can still be achieved when the number density of split-ring resonators is reduced, which relaxes the requirements for processing technology. This research provides a new possible way to improve the second harmonic generation efficiency based on metal metasurfaces.

Surface Lattice Resonances in Self-Assembled Gold Nanoparticle Arrays: Impact of Lattice Period, Structural Disorder, and Refractive Index on Resonance Quality.

Surface lattice resonances are optical resonances composed of hybridized plasmonic and diffractive modes. These collective resonances occur in periodic arrays of plasmonic nanoparticles with wavelength-scale interparticle distances. The appearance and strength of surface lattice resonances strongly depend on the single particle localized surface plasmon resonance and its spectral overlap with the diffractive modes of the array. Coupling to in-plane orders of diffraction is also strongly affected by the refractive index environment and its symmetry. In this work, we address the impact of the interparticle distance, the symmetry of the refractive index environment, and structural imperfections in self-assembled colloidal monolayers on the plasmonic-diffractive coupling. For this purpose, we prepared hexagonally ordered, nonclose packed monolayers of gold nanoparticles using a fast and efficient, interface-mediated, colloidal self-assembly approach. By tuning the thickness and deformability of the polymer shells, we were able to prepare monolayers with a broad range of interparticle distances. The optical properties of the samples were studied experimentally by UV-Vis spectroscopy and theoretically by finite difference time domain simulations. The measured and simulated spectra allow a comprehensive analysis of the details of electromagnetic coupling in periodic plasmonic arrays. In particular, we identify relevant criteria required for surface lattice resonances in the visible wavelength range with optimized quality factors in self-assembled monolayers.

An advanced workflow for single-particle imaging with the limited data at an X-ray free-electron laser.

An improved analysis for single-particle imaging (SPI) experiments, using the limited data, is presented here. Results are based on a study of bacteriophage PR772 performed at the Atomic, Molecular and Optical Science instrument at the Linac Coherent Light Source as part of the SPI initiative. Existing methods were modified to cope with the shortcomings of the experimental data: inaccessibility of information from half of the detector and a small fraction of single hits. The general SPI analysis workflow was upgraded with the expectation-maximization based classification of diffraction patterns and mode decomposition on the final virus-structure determination step. The presented processing pipeline allowed us to determine the 3D structure of bacteriophage PR772 without symmetry constraints with a spatial resolution of 6.9 nm. The obtained resolution was limited by the scattering intensity during the experiment and the relatively small number of single hits.

An absolute surface encoder with a planar scale grating of variable periods

An absolute surface encoder for measurement of absolute in-plane position with a mode-locked femtosecond laser and a planar scale grating having variable periods along the two orthogonal directions is proposed. In the proposed method, the absolute in-plane position is measured through observing the spectra of the coupled groups of the positive and negative first-order diffracted mode-locked femtosecond laser emanated from a single point on the planar scale grating. Due to the dispersive effect of the planar scale grating having variable periods, each of the diffracted modes has a unique angle of diffraction associated with the absolute position information. Therefore, the absolute in-plane position can be detected by obtaining the peak frequencies in the optical spectra of the coupled positive and negative first-order diffracted beams received by dual detector units. The dual-detector configuration of the optical head also contributes to improving the robustness of the absolute position measurement against the angular error motion of the planar scale grating. Furthermore, interference signals capable of being used for the improvement of the absolute position measurement can be generated under the dual detector configuration. Results of the numerical calculations for the theoretical verification of the proposed method, fabrication of a scale grating having a variable period (VLS grating) with interference lithography, design and development of the optical head, as well as the results of basic experiments by using the developed optical head and the VLS grating, are reported.

Optimization methods for achieving high diffraction efficiency with perfect electric conducting gratings.

This work presents the implementation, numerical examples, and experimental convergence study of first- and second-order optimization methods applied to one-dimensional periodic gratings. Through boundary integral equations and shape derivatives, the profile of a grating is optimized such that it maximizes the diffraction efficiency for given diffraction modes for transverse electric polarization. We provide a thorough comparison of three different optimization methods: a first-order method (gradient descent); a second-order approach based on a Newton iteration, where the usual Newton step is replaced by taking the absolute value of the eigenvalues given by the spectral decomposition of the Hessian matrix to deal with non-convexity; and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm, a quasi-Newton method. Numerical examples are provided to validate our claims. Moreover, two grating profiles are designed for high efficiency in the Littrow configuration and then compared to a high efficiency commercial grating. Conclusions and recommendations, derived from the numerical experiments, are provided as well as future research avenues.

Improvement of Abrasion Resistance of Production Equipment Wear Parts by Hardfacing with Flux-Cored Wires Containing Boron Carbide/Metal Powder Reaction Mixtures

Abstract In this work was established that serial traditional hardfacing materials based on the Fe-Cr-C system are not effective for improvement of abrasion resistance of elements of equipment for production of bricks, solid fuel briquettes and for restoration of augers, due to the fact that this equipment works at significant specific and cyclic loads. Features of the coarse-grained structure of Fe-Cr-C based coatings leads to intensive abrasive wear. The aim of this study was to increase a durability of that equipment by using of flux cored electrodes with reaction components of Ti, Cr, Mo, B4C and their combinations to provide synthesis, which leads to fine-grained structure of refractory borides and carbides and their solid solutions with increased hardness. Structure of the hardfacing coatings were investigated by method of metallography, scanning electron microscopy (SEM), electron backscatter diffraction (BSD) mode and energy dispersive X-ray spectroscopy (EDS). Temperature dependences of equilibrium phase amount of the hardfacing materials were calculated by the CALPHAD technique, using JMatPro software. It was investigated that the offered materials are characterized by higher wear resistance at high specific and cyclic loads in comparison with serial production high-chromium hardfacing materials (Lastek, ESAB, Paton IEW). It was established that the abrasion wear resistance at high specific and cyclic loads depends mostly of formation of the structure of hardfacing material, and not the hardness. Also, using of powders of pure metals and their combination as reaction mixture for FCAW leads to fine structure which contains of refractory borides and carbides and their solid solutions.