This article examines approaches to modeling extreme nonequilibrium mass transfer phenomena that occur during the irradiation of high-current electron beams in tool steels, particularly in the context of ultrafast solidification of the molten surface layer. The study investigates the redistribution of elements in P18 steel across the grain area after exposure to a high-current electron beam with an energy of 400 keV, a current density of up to 2 kA/cm2, and a pulse duration of 0.2 μs, A physical and mathematical model of the redistribution process is proposed, and calculations are presented that are consistent with experimental data.

When determining the adhesion force of coatings deposited by the magnetron method, a mathematical model has been developed that allows, based on the calculation of internal stresses, to determine the adhesion force without reference samples. The proposed calculation model using the principle of superposition from several point stress sources made it possible to explain the nature of peeling due to the occurrence of tensile stresses along the depth of the sample

Wire electrical discharge machining (WEDM) is widely used in various fields of production. Its disadvantages include a relatively low productivity rate caused by wire breakages among other factors. In this article, the method of fractographic analysis is used to study a wire that has undergone a breakage during machining. The results indicate that the tool–electrode is subjected to mechanical tension followed by a ductile fracture. The most probable reason of wire breakages is a decrease in the wire cross–section, which can be caused by an electrodes short circuit.

Проволочная электроэрозионная обработка широко (ПЭЭО) применяется в различных сферах производства. К ее недостаткам относится сравнительно невысокая производительность, обусловленная, помимо прочих факторов, обрывами проволоки. В данной статье методом фрактографического анализа проводится исследование проволоки, претерпевшей обрыв в ходе обработки. Полученные результаты свидетельствуют о том, что электрод-инструмент подвергается механическому растяжению, сопровождающемуся вязким изломом. Наиболее вероятной причиной обрывов является уменьшение поперечного сечения проволоки, которое может быть вызвано коротким замыканием между электродами.

The paper provides the results of a short circuit impact on wire breakages during wire electrical discharge machining (WEDM) of AISI 9840 steel by the SODICK VZ300L machine. A method of scanning electron microscopy (SEM) is used for debris size, morphology and shape analysis. The carried out investigation led to the conclusion that the most probable reason of the welding bridge formation is due to the non-spherical (conglomerates) particles' presence with a large number of surface irregularities in a dielectric liquid. A classification of debris particles is proposed from the point of view of their dimensions and ability to overlap the spark gap - "effective" and "ineffective" particles.

The paper consideres the influence of AISI 321 steel microstructure formed by ultrasonic impact treatment on the microrelief regularity of preliminary prepared by turning (Ra=2.15 μm) and grinding (Ra=0.36 μm) austenitic stainless steel samples. The developed technique application for exploration the microstructure influence on the microrelief local irregularity of AISI 321 steel made it possible to establish the absence of a significant effect of twins and grain boundaries on the regular microrelief formation. The most probable reasons for irregular microrelief domain's formation could be considered the design features of dynamic technological module and the quality of initial surface preparation before the ultrasonic impact treatment.

Surface modification of metallic materials and alloys with concentrated energy flows (powerful electron beams and ion plasma flow, laser beams) has been widely used in various fields of manufacturing. The aim of physical and mechanical properties modification is to improve the performance of the critical parts fabricated from modified materials. The mentioned energy impacts give rise to radiation, thermal and mechanical effects causing the changes in morphology, microstructure, elemental and phase composition of the surface layers, which in turn may lead to hardness, wear corrosion resistance and red hardness increasing of modified materials. However, as experimental investigations are shown, in some cases irradiation promotes the crystal defects’ occurrence and often non-uniform heating leads to the cracks’ formation in the surface layers. Thus, selection of incident electrons energy, its current density and pulse duration, taking into account the thermal stress state, is an actual problem of modern radiation technologies. This paper provides a numerical solution of differential equations in partial derivatives for the temperature fields’ computation as well as radial and axial thermal stresses distribution in R6M5 (AISI M2) high-speed steel exposed to medium-energy (up to 400 keV) high–current (up to 1 kA/cm2) pulsed (up to 1 μs) electron beam radiation. The obtained results can be useful in the optimal modes selection of tool steels and products at surface radiation treatment and evaluation of their service life.

This paper provides the mutual low–temperature mass transfer in binary systems obtained by magnetron sputtering of niobium onto a heated copper substrate. Based on the kinetic equation of diffusion, the distribution of the niobium through the substrate’s depth at temperatures of 100, 200 and 300 °C is calculated. The method of calculating the concentration profiles of niobium, proposed in the manuscript, was verified using experimental data of energy–dispersive analysis.

The paper provides an analysis of the influence of the Rehbinder effect, electrical erosion and wire tension on breakages during wire electrical discharge machining (EDM) of steel 36CrNiMo4 (the analogue of AISI 9840) by the SODICK VZ300L machine. A classification of wire breakages (explicit and implicit) is proposed and the reasons for both breakage types are considered. The methods of optical microscopy, scanning electronic microscopy, fractography, and tensile testing of the wire in the air atmosphere, as well as pure and impure deionised water, are used to demonstrate that the Rehbinder effect and microdamage caused by electro-discharge do not have a substantial influence on implicit brass wire breakages. The experimentally determined average value of the amorphous zone width (8.4 pm) of an eroded wire was used during its stressed-state simulation, resulting from the non-uniformity of the temperature distribution throughout the wire depth. To estimate the influence of thermal stresses on implicit wire breakages, the internal thermal stresses calculation algorithm, based on the generalised Hooke's law in a differential form and the consideration of stresses caused by thermal wire expansion, is proposed. Considering the wire pre-tension acting along the longitudinal wire axis (365 MPa) caused by rollers, and the maximum axial thermal stresses (167 MPa) obtained by simulation, the total tension of an eroded wire is 532 MPa, which is significantly lower than the tensile strength of the eroded wire (891 MPa) determined experimentally. The most probable reason for implicit wire breakages is violation of the continuity wire machine feedback following random large EDM debris sticking to the wire and workpiece. The investigation leads to the conclusion that the most probable cause of explicit breakages is short circuits.

Conductive thin films formation by copper and silver magnetron sputtering is one of high technological areas for industrial production of solar energy converters, energy–saving coatings, flat panel displays and touch control panels because of their high electrical and optical properties. Surface roughness and porosity, average grain size, internal stresses, orientation and crystal lattice type, the crystallinity degree are the main physical properties of metal films affecting their electrical resistivity and conductivity. Depending on the film thickness, the dominant conduction mechanism can affect bulk conductivity due to the flow of electron gas, and grain boundary conductivity. The present investigation assesses the effect of microstructure and surface topography on the electrical conductivity of magnetron sputtered Cu and Ag thin films using X–ray diffraction analysis, scanning electron and laser interference microscopy. The highest specific conductivity (78.3 MS m–1 and 84.2 MS m–1, respectively, for copper and silver films at the thickness of 350 nm) were obtained with the minimum values of roughness and grain size as well as a high degree of lattice structuredness.

The paper deals with the results of experimental research carried out by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to define, how the modes of wire electrical discharge machining (WEDM) influence on the elemental and the phase composition of E110 zirconium alloy's surface layer. Investigation of the phase composition allowed us to determine the main alpha and delta phase's distribution through the depth of zirconium surface layer, in common with phases of oxygen, copper, zirconium, and niobium specific compounds. It was also established the maximum depth of the defect level containing amorphous phase for all of WEDM modes, and proposed the grinding and polishing as potential mechanical methods of its removal.

Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings' forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings' durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary "steel-coating" systems.

Niobium and niobium thin films are widely used in various fields of modern science and technology: in the electronics industry, in a nuclear medical imaging technique, in the information technology, in superconducting cavities technology etc. The grain size of thin niobium films depends on its thickness and the film’s stoichiometry can be varied as a function of thickness. Thus the problem of thickness control has a great practical importance in all fields of niobium films application. The focus of this study was to perform an experimental calibration of STC–2000A deposition controller for niobium target on ADVAVAC VSM–200 setup and to conduct a grain size, roughness and stoichiometry research by scanning electron microscopy, X–ray diffraction and laser interference microscopy of niobium films produced by RF magnetron sputtering with the thickness range from 200 nm to 400 nm and 50 nm step.

The article considers the research results of the << friction surface-solid lubricant >> system with molybdenum disulfide suspension before the ultrasonic impact treatment. An average particle's size detected in the molybdenum disulfide powder is 10.9 mu m. The comparative analysis of MoS2 particle's distribution as per size and valleys' sizes on turned and ground surfaces allow us to make a conclusion regarding the comparability of these values and principal possibility of micro valley's filling with MoS2 particles. MoS2 attachment to the near-surface layer of steel AISI 321, subjected to the turning (Ra= 2.15 mu m) or grinding (Ra= 0.36 mu m), is implemented by means of the microasperities deformation by an ultrasonic tool depending on the initials surface morphology.

For material selection of protective metal coating, deposited on the products' surface with cylindrical symmetry by magnetron sputtering and exposed to intense heat loads during pulsed operation mode, it was executed numerical simulations of the temperature fields and the stress state caused by pressure and uneven temperature distribution. It was determined a coatings' material satisfying the minimum of internal stresses, which is one of the main criteria of their service life. Based on the calculation results titanium provides the maximum reduction in the internal stress while the usage of molybdenum as a coatings' material leads to the greatest decrease of pulsed temperature impact to the binary "steel coating" systems with cylindrical symmetry.

In the process of metallic materials treatment by pulsed laser beams with nanosecond duration occurs extremely rapid and intensive heating of their surface. In this case a thin surface layer of material is heated to the boiling point and rapidly evaporates. This leads to arising substantial forces of reactive nature which significantly influence on the shape of the solidified melt and in some cases may cause deformation of the underlying layers. The considered question is relevant in the research of precision treatment of miniature products by laser beams. A metallic powder with microfine material structure was selected as the object of research and was exposed to laser irradiation with nanosecond duration. At the core of reactive forces calculation used the approach similar for laser rocket engines. The paper also presents the model and the results of the forces and the reactive recoil impulse calculation occurring during laser impact to the microfine metallic powder.