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The development of modern high-tech industries of industrial production is impossible without the development of new methods for processing materials with high mechanical characteristics. There is a growing need for an increase in the proportion of parts made of aluminum alloys, a more complex configuration of cast parts, an increase in their reliability and durability in operation, etc. All this poses for metallurgists and foundry workers the task of creating new technologies for producing alloys, improving the technical and economic characteristics of structural materials, improving the quality and reducing the cost of castings.Hypoeutectic silumins have good casting properties, good weldability, machinability and corrosion resistance. However, they are prone to the formation of a coarse needle-like state, which reduces their useful characteristics. To eliminate this phenomenon, it is necessary to apply special technologies and the most common is their modification, which provides grain refinement. This makes it possible to use silumins for the manufacture of castings of complex shapes with increased density and low shrinkage porosity. Such parts can withstand average loads in critical units. Aluminum-silicon alloy AK7 or (ASi7Mg0.3) is a typical silumin, which is in demand in the automotive industry, construction, aircraft construction, machine, automobile and tractor production. It is appreciated for its good casting properties, weldability, machinability and corrosion resistance.

The article investigates the possibility of replacing the AlSi7Mg0.3 alloy used for manufacturing automotive wheel disks with eutectic silumin alloyed with magnesium. The crystal lattice constant, structure, hardness and mechanical properties of eutectic and hypoeutectic silumins have been determined, and their comparative analysis has been performed. It is shown that the heat hardenable eutectic silumin can be used for manufacturing cast automotive wheel disks instead of a less adaptable to manufacture AlSi7Mg0.3 alloy.

Barothermal treatment of the cast binary alloy Al–8 at % Si has been performed at 560°C/100 MPa/3 h. A microstructure with silicon particles with an average equivalent diameter of ~2.9 microns has been formed in the alloy. Barothermically treated silumin had a yield stress of 67.6 MPa, a tensile strength of 141.6 MPa, and a relative elongation of 34.1%. Cold deformation of the alloy to obtain a foil with a thickness of 16 microns has been realized. A decrease of the aluminum and silicon crystal lattice constants has been established, which is more noticeable at the maximum deformation of the alloy. When deformed, a textured alloy structure is formed with an axis of {100} along the rolling direction. The mechanical properties of the deformed alloy are determined, and the values of yield stress, tensile strength, and elongation equal to ~265 MPa, 305 MPa, and 5.5%, respectively, are obtained for a tape with a thickness of 900 microns. With a higher degree of deformation, for a tape with a thickness of 90 microns, these characteristics have values of ~146 MPa, 165 MPa and 1.4%, respectively, and for the foil with a thickness of 16 microns, ~180 MPa, 196 MPa and 0.3%, respectively.

The results of structure and phase composition investigation in hypereutectic silumin alloy with 25 at. % Si content after high-energy pulsed compression plasma flows impact are presented in the work. The compression plasma flows impact with an absorbed energy density 25 – 40 J/cm2 allows to modify the sub-surface layer with a thickness up to 30 – 32 µm due to its melting and high rate solidification. By means of X-ray diffraction method, it was found the formation of two silicon phases with different grain sizes. The high-dispersed structure of silicon is presented in the Al-Si eutectic while the silicon phase with coarse grains exists in the primary crystals. The obtained results are the basis for a new method development for nanostructuring of the surface layers of hypereutectic silumin alloys increasing its wear resistance.

To improve functional properties of pre-eutectic silumins there are used many different methods having a complex effect upon processes of structure formation and physical-mechanical properties of alloys. In this paper there is offered a method for alloy operation characteristics increase by the example of wear-resistance by the impact of nanosecond electro-magnetic pulses (NEMP) upon silumin melt AK7ch (AL9). Melt illumination was carried out with the generator (NEMP) (GNI-01-1-6) submersible rod radiator. The melt was overheated to 900ºC and processed with NEMP with the length up to 25 min after that it was cooled at a rate of 20ºC/min. Slow cooling contributed to the formation of a structure close to equilibrium. Cylindrical ingots with a diameter of 0.06 m (60mm) and a height of 0.06 m (60 mm) were obtained. Wear-resistance was defined on a cross cut of ingots according to GOST 23.208-79. As a standard of comparison were used non-irradiated samples of silumin. It is defined that melt NEMP processing changes considerably parameters of crystallization, structure formation and increases silumin properties. At abrasive wear, silumin wear-resistance changes from the duration of melt electro-pulse processing according to an extreme dependence with the evident maximum at melt irradiation in the course of 15 min. At that in the edge area of the ingot wear-resistance increases by 1.54 times, and in the central one – by 1.34 times. This effect is explained by the fact that during melt NEMP processing during 15 min the characteristics of alloy micro-structure change considerably: morphology and dimensions of structural constituents. At that there is formed a qualitatively new fine structure of a non-dendritic type which ensures maximum values of alloy wear-resistance. The data obtained allow developing technology of wear-resistant silumin fusion intended for operation under abrasive wear conditions.

The article examines a number of regularities in the production of primary cast ingots of AlSi7Mg, AlSi7MgSr, AlSi11Mg, and AlSi11MgSr. Peculiarities of melting and cast of these alloys, as well as the effect silicon and strontium have on the formation of the shrinkage cavities, have been explored. It has been demonstrated that strontium, when used as a modifier, changes not only the morphology of silicon, but also the nature of solidification and shrinkage of the alloy. Defects formed in the ingots manufactured from near – eutectic AlSi11MgSr alloy have been studied in greater detail.

The influence of the effect of combining different types of processing based on the physical force acting on the surface of conductive materials and the electrochemical active action of electrolytes acting as a cutting fluid is considered. The experiments carried out and show a significant effect of these types of processing on the surface quality and the provision of the initial various physical and mechanical properties of the processed materials. The article presents various dependencies of qualitative parameters for the implementation of shaping processes using such blade processing operations as turning, threading in holes of small diameter and expanding the holes. With combined processing methods, the process of forming the finish surface is due to the combined action of the cutting tool and the anodic dissolution of the metal under the influence of an electric current in the electrolyte solution. The application of this method allows obtain higher quality parameters when machining aluminum and copper alloys, the surface formed during processing, including the preservation of such special characteristics of certain materials, such as porosity.

To assess the effect of the mould filling modes on the content of oxide films in castings, special criterion is proposed that provides prediction in the contamination of chill castings mаde of aluminum alloys by using modern computing tools to simulate the moulds casting process on computer. It is noted that decrease in the value of the contamination criterion by using alloys with low content of Mg or without this component reduces the possibility of controlling the distribution of oxides in the casting, other elements of the casting mould and using the concentration of oxides, for example, in washers to control the mechanical properties of cast products. This is due to increase in the duration of oxidation processes in gas-tight mould with such change in the composition of the casting material.

In everyday life the use of vehicles has expanded immensely for some ventures and house hold applications, likewise the running time of engine cycle is exceptionally long. Thus because of the consistent running enormous measure of heat is produced. At the point when this heat isn't appropriately disseminated, the engine gets more fragile very soon and life of the engine declines because of the heat development. To build the life of the engine, heat dispersal is expanded by giving fins at external of engine chamber. The shape of the fins and the material used for the fin increases its heat dissipation capacity and in turn increases the cooling of the engine for proper functioning. The present work focuses on the design of fins of circular and tapered shapes for a 2-stroke engine. The temperature distribution and the heat dissipation along the fin surface of two shapes has been observed by a steady state thermal analysis. Alusil and Silumin has been selected as the fin materials and a computational evaluation has also been done using FEM. A better shape of the fin along with a suitable material has been selected based on the results observed by FEM and on comparison with the existing shape and material of the fin.

Effects of the high-energy compression plasma flows on the structure, elemental composition, and phase state of Al-44 at.% Si hypereutectic silumin alloy have been investigated. Using scanning electron and optical microscopy it was found decreasing in grain size of both primary silicon particles and Al-Si eutectic parts with increase of absorbed energy density of compression plasma flows. The primary silicon crystals were dispersed down to 300 nm in the result of high cooling rate of the melted layer after its homogenization by means of hydrodynamic mixing. It was found that increase in the absorbed energy density, homogenization of elemental composition in the modifies layer occurs due to increase in lifetime of the melted state and more efficiency mixing process.

A laser optoacoustic method for quantitative assessment of the volumetric porosity of cast dispersion-strengthened metal-matrix composite materials has been proposed and experimentally implemented. The method is based on a statistical analysis of the distribution of amplitudes of backscattered broadband pulses of longitudinal acoustic waves in the tested materials. Laser excitation and piezoelectric recording of ultrasound is implemented with one-way access to the test object using a special laser-ultrasonic transducer. Silumin-based composites reinforced with silicon carbide microparticles in various volume concentrations (0.033–0.135) and composites obtained by reaction injection moulding based on aluminum reinforced with intermetallic $${\text{A}}{{{\text{l}}}_{3}}{\text{Ti}}$$ (volume concentration 0.04–0.115) have been studied. For both types of composites, the distribution of amplitudes of backscattered ultrasonic signals is approximated by a Gaussian distribution function applicable for a large number of statistically independent quantities. The empirically obtained dependence of the half-width of this distribution on the volumetric porosity of composites of two different types is approximated by the same linear function regardless of the manufacturing technology, as well as of the type, size, and concentration of strengthening particles.

Technologies for the 3D printing of metallic powders are being increasingly extensively used around the world as alternatives to casting and machining to manufacture components of complex shapes and prototypes. Silicon-alloyed aluminum alloys are the most widely used materials in the selective laser melting technologies, which is caused by the price of these alloys and their high manufacturability for the layer-by-layer fused deposition, owing to their low susceptibility to hot cracking under thermal and shrinkage stresses. High rates of cooling the melt facilitate the formation in the material of ultradispersed silicon-containing phases, which results in increased strength. In the article, exemplified by two cast alloys (AK7ch and AK9ch), the speeds of the process of building up the products by the selective laser melting technology have been determined at a laser-beam power of 300 and 325 W and an energy density within the range 89–32 J/mm3. It is shown that, for the AK9ch alloy, lower porosity values are achieved within the investigated energy density range when compared with the AK7ch alloy and better mechanical properties of the alloy with a higher silicon content are achieved within the range of lower laser-beam energy densities than for the alloy with a lower silicon content. The mechanical properties of the materials produced under the optimal selective laser melting conditions comply with the most stringent requirements for the mechanical characteristics of the castings of the AK7ch alloy upon heat treatment.

Aspects of increasing the strength of silumin due to the introduction of ultrafine silica powders into its melt are considered. The calculation of the surface energy of silicon oxide nanoparticles showed the promise of this modification. The method is proposed for increasing the adhesion of silicon to aluminum, due to the surface-active properties of magnesium and the high surface energy of nanoparticles, which contributes to the formation of chemical compounds of silicon with aluminum, and as a result, to hardening of the alloy. Due to the large difference in the surface energies of magnesium and silicon, the possibility of producing Si @ Mg core-shell nanoparticles in the one-step method under the action of an electron beam has been shown. The layout of substances in the graphite crucible, the dependence of the electron beam current to obtain Si @ Mg nanoparticles are presented.

The microstructure, the phase composition, the component distribution, and the grain structure of the commercial eutectic Al–12.2 Si–0.2 Fe (at %) silumins formed at cooling rates of 102 and 105 K/s are studied. Three phases are detected in the alloy after solidification at both cooling rates: α-aluminum, silicon, and an iron-containing phase. The bulk samples have a heterogeneous dendritic structure with large dendrites of an aluminum-based solid solution, and a eutectic lamellar mixture of aluminum and silicon filling the interdendritic space. The melt-quenched foils are characterized by a homogeneous microstructure over the thickness; however, they have a layered structure. The rapidly solidified foils also have a homogeneous granular structure through the thickness and no pronounced texture. The mechanisms of solidification and microstructure formation are proposed for both the bulk samples and the melt-quenched foils.

Tribological tests of a hybrid composite (Al–12Si)–40Sn prepared by sintering mixtures of powders of silumin and pure tin were carried out using the pin-on-disk scheme. It has been established that an increase in the sliding velocity decreases the wear intensity of the composite upon dry friction, while an increase of the load leads to the opposite result. The data obtained indicate that the main contribution to the wear of the composite comes from the delamination of strongly deformed subsurface layers of the material. With an increase in the sliding velocity, the mechanism of the wear does not change, but, because of the heat-induced softening of the material, wear particles of the steel counterbody are pressed into it that “plate” the surface of the sample and reduce its wear intensity.

Явление структурной наследственности получило промышленное применение, несмотря на то что «механизм передачи наследственных признаков расплаву, их сохранение, зарождение в нем новых признаков и передача их твердому металлу - все это сложные, во многом неизученные вопросы» (Б.А. Баум с коллегами). На примерах стали, чугуна и алюминия предпринята попытка обоснования предположения, что одним из механизмов передачи наследственных признаков может быть эффект «памяти жидкости», который заключается в сохранении ее свойств при очень сильном разбавлении. The phenomenon of structural heredity is used by industry, although «the mechanism of transmission of hereditary traits to the melt, their conservation, the generation of new traits in it and their transfer to solid metal are all complex, largely unexplored issues» (B.A. Baum with colleagues). On the examples of steel, cast iron and aluminum, an attempt was made to substantiate the assumption that one of the mechanisms of transmission of hereditary traits could be the effect of «fluid memory», which consists in maintaining its properties with very strong dilution.

The study reports on the electron-beam processing (energy of accelerated electrons 17 keV, electron beam energy density ES = 10, 20, 30, 40, and 50 J/cm2, pulse duration 50 and 200 μs) of Al-10wt%Si-2wt%Cu alloy (silumin) surface. The important outcome to emerge from the study is a correlation between surface microhardness and electron beam energy density. As revealed, a maximal microhardness value is at ES = (30–40) J/cm2, being more than 1.6 times higher than the characteristic of the untreated material. The research has pointed out the electron-beam processing of silumin at ES = 10 J/cm2 causes the intensive destruction and microcracking along grain boundaries with particles of intermetallic compounds, as well as the globularization of cementite lamellae in eutectics. The irradiation of silumin by an electron beam (ES = 30–50 J/cm2) is shown to bring about the origination of micropores in the surface of samples, the dissolution of silicon, the globularization of intermetallic inclusions; in addition, a sub-micro-sized crystal structure of high-speed cellular crystallization forms. Finally, the electron-beam processing of silumin leads to the saturation of Al-based crystal lattice with alloying and impurity elements.

The decay mechanism of silicon particles in silumin in the thermal effect zone of low-energy high-current electron beam is proposed. Its essence consists in the fact that under the effect of the mechanical stresses the interface of silicon inclusion with aluminum matrix becomes instable resulting in the decay of silicon particle. It was supposed that the instability was the analog of Rayleigh-Taylor instability. The mechanical stresses arising due to the discrepancy of the elastic moduli and the linear expansion coefficients of the inclusion and the matrix are the analogs of gravity force. The analysis of the initial stage of instability within the frameworks of the visco-potential approximation has shown that the dependence of the rate of perturbations’ growth has only one maximum which falls on the wave length of the order ≈ 500 nm that is 5-fold higher than that of the experimental data. Such a discrepancy may be explained by the fact that when developing the model the temperature of the silicon inclusion and the aluminum matrix was considered to be constant, similar and being equal to the eutectic temperature of silumin. In fact, the temperatures of the inclusion and the matrix are different. To take into account the influence of these facts on the instability of the interface the new investigations are necessary.

The paper presents the results of modification of the silumin surface layer using a multicycle processing technique which combines the formation of the film (titanium)-substrate (silumin) system and the low energy high current pulsed electron beam (LEHCPEB) irradiation of submillisecond duration in one cycle. A KOMPLEX plasma-ion-assisted electron-beam setup (Institute of High Current Electronics SB RAS, Tomsk, Russia) is used for silumin treatment. Titanium is used as an alloying element. The thickness of the deposited film is 0.5 μm in each alloying cycle, the number of which is 1, 5 and 10. Surface alloying includes ion-bombardment cleaning and heating by hot and hollow cathodes of argon plasma discharge, with negative bias voltage supply to the specimen (initial heating up to preset temperature, surface cleaning and activation); plasma-enhanced chemical vapor deposition of metal films (argon is used as a carrier gas); and LEHCPEB irradiation of the film (titanium)-substrate (silumin) system. It is shown that multicycle alloying of the grade АK12 silumin (G-AlSi12, DIN, Germany) with titanium leads to a dissolution of silicon and intermetallic inclusions in the surface layer up to 30 μm thick, the formation of submicro- and nanocrystalline multiphase structure with the microhardness and wear resistance, which are 1.4 and 14.2 times higher than in cast silumin.

In this paper we performed comparative studies of the tribological properties of the AlSi15Cu3 antifriction silumin and BrOTsS5-5-5, BrOF10-1, and BrAZh9-4 bronzes during friction in the I-20A lubricant environment in a wide range of sliding speeds and test pressures. It has been shown that no accumulation of defects occurs in the crystal lattice in its surface layers during the friction of an aluminum alloy. This is associated with the low recrystallization temperature of the aluminum matrix phase of the alloy. We conclude that AlSi15Cu3 antifriction silumin is a promising material for replacing expensive antifriction bronzes in highly loaded friction units.

The process of mixed oxide coatings formation on a high-silicon aluminum alloy in a cobalt-containing pyrophosphate electrolyte by the plasma-electrolytic oxidation (PEO) method is studied. It was shown that AL25 chemical composition heterogeneity causes the consumption of a part of the anode current to homogenize the treated surface, which is reflected in minimizing the content of doping components at the initial processing stage. It was established that the growth of mixed oxides Al2O3·CoxOy relative mass is a function of time with a maximum at 55 minutes. The chemical, phase composition and surface morphology of the formed oxide layer depend on the oxidation time. The catalytic component content in the surface oxides varies from 0.2 to 23.3 at.% with an increase in processing time of 10 to 60 minutes. Maximum cobalt incorporation into the oxide layer occurs at PEO of 35–50 minutes, while the silicon content in the surface layers does not exceed 2 at.%, which is favorable for the catalytic properties. The cobalt oxide, preferably Co3O4, incorporation in the alumina α-Al2O3 matrix is visualized by the blue-violet color steroidal surface structures in the sites of micro-arc discharges. The alumina cobalt oxide mixture layers are characterized by a developed micro-globular surface which consists of spheroid conglomerate with an average size of 1–2 microns. There are some amorphous phases in the structure of mixed oxides due to non-equilibrium PEO conditions. The set of detected factors is a prerequisite for the high catalytic properties of oxide coatings. A promising field of Al2O3·CoxOy systems application is intra-cylinder catalysis in internal combustion engines.

The structure and mechanical characteristics of alloy AK9ch are studied after different treatments involving homogenization and modification of the melt. The micromechanism of crack growth in alloy AK9ch after the treatments is investigated. The composition of the phases is studied quantitatively with plotting maps of the distribution of elements in them. The changes in the morphology of the individual phase components due to the modifying and due to joint homogenizing and modifying are determined.

In the present study, experimental research was carried out to determine the effect of the processing tool wear on the mutual change in the average statistical amplitude parameters of acoustic emission signals. Acoustic emission signals were recorded when turning silumin. The research was aimed at finding parameters to determine the occurrence of critical wear of the processing tool. It is shown that the recorded signals are continuous. The statistical amplitude parameters of the acoustic emission signals were processed under normal and catastrophic wear of theprocessing tool. It has been determined that the development of normal and catastrophic wear of the tool leads to a decrease in the values of the statistical amplitude parameters of the recorded signals. However, no peculiarities were found in their change to determine the developing type of wear. Meanwhile, at different time intervals, there was an anticipating increase or decrease in one of the statistical amplitude parameters of the acoustic emission signals. The processed parameter was a coefficient characterising a mutual change in the statistical amplitude values of the recorded signals. It has been determined that absence of the tool wear is characterised by stable values of the calculated coefficient in time. The occurrence and development of catastrophic wear leads to an outburst of the value of the calculated coefficient with its subsequent accelerated decrease to the destruction of the tool. The emergence and development of normal wear leads to an increase in the value of the calculated coefficient with a subsequent transition to a sawtooth change and a gradual decrease of its size. The obtained regularities can be used when devising methods for controlling and monitoring the condition of the tool during the mechanical processing of materials, including monitoring the state of the processing tool in robotic industries

The paper concerns the mechanical properties of hypoeutectic Al-Si alloy (silumin) with the addition of Cr, Mo, V and W. Changes in microstructure under the impact of these elements result in a change in the mechanical properties. Crystallization of Al-Si alloys determines grain size reduction, which causes a significant increase in their strength properties. Crystallization subjected to modifications through the influence of alloying additives can be described by the cooling curve run. Statistical relationships between the characteristic values of cooling curves and mechanical properties are investigated with data mining techniques of regression, especially regression trees. Such knowledge could provide an ability of a property prediction on the basis of cooling curves in terms of the benefits of a short time of the curve registration.

The analysis of the gradient structure-phase states and nanohardness of hypoeutectoid silumin at 120 μm depth after the processing by high intensive electron beams in the regime of top layer melting has been carried out. It has been shown that depending on the depth to the surface of irradiation the electron beam processing leads to the dissolution of the primary inclusions of silicon and intermetallides and the formation of structure of high-speed cellular crystallization of aluminium and the grains of plastic eutectic. A 1.5‒2 fold decrease in the concentration of the alloying elements has been detected. The hardness of irradiated silumin changes in a nonmonotonous way and reaches the maximum values exceeding the hardness of the initial state by 3.8‒4.2 times in the layer located at 30–50 μm depth. The interpretation of the observed changes in structure and hardness on irradiation has been given.

An Al–Si eutectic alloy was synthesized by the selective laser melting (SLM) method using a pilot wrought Al-Si powder (of Russian AKD-12 grade) as the starting material. On the basis of electron microscopy, the microstructure of the SLM alloy was certified with EDS mapping of elements (Al and Si). It has been established that the main structural component is an Al-based solid solution with a cellular-dendritic structure (with an average cell size of ~500 nm). The Si phase, which is a component of the eutectic, is located at the boundaries in the form of rounded crystals about ten nanometers in size. This paper presents the results of measuring the mechanical and nanomechanical properties, which show the competitiveness of the use of the pilot (experimental) powder.

The structure, phase composition and tribological properties of surface layers of hypoeutectic silumin after the complex processing including the electroexplosion alloying with the yttrium oxide powder in different regimes and the subsequent electron beam processing have been analyzed by the methods of modern physical material science. With respect to the initial silumin the ≈20-fold increase in the wear resistance and ≈1.5-fold decrease in the friction coefficient have been detected. The complex processing is accompanied by the formation of the multiphase submicro—nanocrystalline layer up to 80 μm in thickness enriched by yttrium and oxygen atoms responsible for the multiple increase in the wear resistance. At the complex processing according to the first regime of electroexplosion alloying (EEA) (Y2O3 powder mass—0.0589 g, discharge voltage—2.8 kV) with the subsequent electron beam irradiation, the major phase of the modified layer is the solid solution based on Al (≈71.2 mass %), the remaining phases are SiO2, YAlO3, YSi2. The 1.5-fold increase in the mass of Y2O3 powder at EEA and 1.1-fold decrease in the discharge voltage is accompanied by the increase in the quantity of phases, the significant (more than 2.5-fold) decrease in the content of the solid solution based on Al, the ≈2.2-fold increase in the content of silicon oxide, the presence of yttrium oxide and metallic yttrium.

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.

The aim of this experiment was to investigate the influence of the Sr modifier in the Al-Si eutectic alloy on the structure change and its mechanical properties. For this reason, an Al-Si7Mg0.3 hypoeutectic silumin alloy was modified with the aim of improving the mechanical properties of the material, mainly by increasing the ductility and strength. The subject of investigation was analysis of morphology of excreted eutectic silicon. In order to investigate the surface, metallographic cross-sectional specimens were prepared using light and electron microscopy. A static tensile test was performed for detailed examination. It has been found that the addition of the AlSr10 modifier and, over the time of modification of 1 to 2 hours, has increased the mechanical properties, in particular the ductility.

The analysis of structure, phase composition and tribological properties of surface layers of hypoeutectic silumin after complex treatment including the electroexplosion alloying by yttrium oxide powder in different modes and subsequent electron beam processing was done by the methods of modern physical material science. The complex treatment is accompanied by the formation of multi–phase submicro – nanocrystalline layer up to 80 μm thick enriched by yttrium atoms and being responsible for the increase in wear resistance. It is shown that Y atom concentration in the modified layer depends on electroexplosion alloying (EEA) mode. The distribution of Y atoms in the layer depends on the mode of EEA as well.

The initial structure of AlSi9Mg alloy is com posed of granular and acicular β phase, with α phase as matrix. The hard, irregular, often pointed β phase is responsible for the poor mechanical properties of said alloy. This composition is responsible for the alloy's low strength parameters, and it limits the extent of practical applications. This study presents the results of modification of an AlSi9Mg alloy with strontium, boron and titanium in different ranges produced as a melted modifier added as powders and as rod. The influence of the analyzed additions on the microstructure and tensile strength of the silumin was presented in graphs. The used treatments of a hypoeutectic AlSi9Mg alloy improved the alloy's properties. The results of the tests indicate that the mechanical properties of the modified alloy are determined by the sequence in which the components are introduced to the alloy.

—The hardness and the tribological properties of the AK10M2N silumin subjected to irradiation by a high-energy pulsed electron beam with an energy density of 35 J/cm2 are studied. As compared to the as-cast state, the microhardness of the surface layers increases by ≈20% (up to ≈1.2 GPa), the friction coefficient decreases by a factor of ≈1.3 (down to 0.42), and the wear parameter decreases by a factor of ≈6.6 (down to 0.74 × 10–3 mm3/(N m)). These changes are shown to be caused by the dissociation of silicon and intermetallic compounds in the surface layer during irradiation by a high-energy pulsed electron beam.

The paper presents the results of tensile strength tests of AlSi21CuNiMg silumin made on a test stand. Silumin was under examination in an unmodified state and after modification with AlCu19P1.4 master alloy in quantity of 0.2% in relation to the mass of the alloy. Using a scanning microscope, the surface fractures obtained from tensile tests were tested. The structure and profiles of fractures were examined using an optical microscope. Modification of the tested silumin resulted in a favorable fragmentation and regular distribution of the crystals of the primary silicon in the alloy structure, which led to an almost twofold increase in the strength of the silumin samples at the final solidification stage from 3.5 to 6.6 MPa. As a result of these changes, the resistance of silumin to hot cracks should increase, which is of great importance when casting hypereutectic silumin in a metal mould that strongly inhibits the shrinkage of the castings.

We study the influence of gas porosity caused by the presence of dissolved hydrogen on the mechanical properties of Al–Si alloys. The results are obtained by testing cast samples with identical contents of hydrogen and a given (atomic or molecular) form of hydrogen inclusions. The dependence of the mechanical properties of alloys on the density index is statistically established. It is shown that if the density index increases and hydrogen is released in the atomic form, the mechanical properties remain practically unchanged, whereas the presence of hydrogen in the molecular form in silumin deteriorates the mechanical properties of the metal.

A survey of occurring methods of silumin production is presented. The possibility of fabricating casting alloys using amorphous microsilica is shown. Various methods of introducing silicon dioxide particles into the aluminum melt are studied and approved, notably, in the form of pelleted “aluminum powder–SiO2” master alloys, by admixing particles into the melt at the liquidus temperature and by introducing SiO2 into the melt jointly with the argon flow. Calculations of the formation enthalpies and variations in the Gibbs energy of the reduction of silicon from its oxide by aluminum are performed. The thermodynamic probability of formation of silumins using amorphous microsilica is shown based on these calculations. The influence of alloying additives and impurities on the process flow of silicon reduction is determined. The possibility of using magnesium as the surfactant additive, making it possible to remove oxygen from the surface of dispersed particles and reduce silicon from its oxide, is revealed. It is determined that the fabrication method of casting silumins by introducing amorphous silica preliminarily heated to 300°C into the aluminum melt (t = 900°C) jointly with the argon flow (with the subsequent intense stirring) jointly with the argon flow (with subsequent intense stirring) possesses the largest efficiency, because it makes it possible to fabricate aluminum–silicon alloys with a Si content higher than 6 wt % and microstructure corresponding to hypoeutectic casting silumins. The industrial implementation of the proposed method will make it possible to increase the efficiency of the occurring production process of silumins due to the economy of resources spent on purchasing commercial crystalline silicon. Moreover, this technology will promote lowering the environmental load to the surrounding medium due to the reduction of volumes and subsequent elimination of sludge fields, which are landfills for storing dust from gas purification systems of silicon production that contain up to 95 wt % amorphous microsilica.

The structural phase states and silumin’s defect substructure of silumin hypoeutectoid composition subjected to electron beam processing with the following parameters: energy density—25 J/cm2, pulse duration—150 µs, number of pulses—3, pulsed repetition rate—0.3 Hz were analyzed by methods of modern physical material science. The irradiation of the surface leads to the melting of the surface layer, the structure formation of high-speed cellular crystallization of submicron dimentions and the repeated precipitation of the second phase particles. The cells formation of two types: those free from precipitations of the second phase and those containing the lamellar eutectic Al–Si was revealed. The cells are separated by the second phase interlayers containing the particles of Cu15Si14Al4Cu9, silicon and copper. As the distance from the surface of irradiation increases the layer containing the second phase inclusions of quasi—equilibrium shape are defined along with the crystallization cells. It is indicative of the occurance of the globularization processes of silumin’s structure on electron beam processing.

The paper presents a new technological scheme for obtaining bimetallic materials of the composition "aluminum casting alloy - sintered iron powder" by the method of joint stamping. The results of experimental studies of the effect of process conditions on the physicomechanical properties of the starting materials and the adhesive strength of the final bimetal blank are presented.

The paper presents a review of existing methods to produce silumins. The possibility of obtaining foundry alloys using amorphous microsilica is shown. Different methods of adding SiO 2 particles into molten aluminum are studied: in the form of aluminum powder — SiO 2 master alloy tablets, particle mixing in the melt at the liquidus temperature and introducing SiO 2 together with a stream of argon. The paper provides calculations of Gibbs energy formation and change enthalpy for silicon reduction by aluminum from its oxide. Calculations demonstrated the thermodynamic possibility of silumin production using amorphous microsilica. The effect of alloying additives and impurities on the silicon reduction behavior is determined. It is found that magnesium can be used as a surface-active additive to remove oxygen from dispersed particle surfaces and reduce silicon from its oxide. It is determined that the method of aluminum-silicon alloy production by introducing amorphous microsilica preheated to 300 °С into the aluminum melt (t = = 900 °С) together with argon stream (with subsequent intensive mixing) features higher efficiency since it ensures producing aluminum-silicon alloys containing more than 6 wt.% of silicon and microstructure of pre-eutectic foundry silumins. Industrial application of the proposed method will improve the efficiency of the existing silumin production process due to savings on purchasing commercial crystalline silicon. Moreover, this technology will minimize the environmental impact by reducing the volume and subsequent eliminating sludge fields used as landfills for storing dust from silicon gas treatment systems containing up to 95 wt.% of amorphous microsilica.

Compression tests of sintered (Al–12Si)–xSn composites have been carried out and it has been found that the flow curves of these composites consist of up to eight alternating linear and parabolic deformation stages. The strain-hardening coefficient θi of the material at each stage is constant. With increasing the order number of the stage i, θi decreases and can take a negative value. In the general case, θ = $$\theta _{i}^{n},$$ where n = 1 at the linear flow stage and n = 0.5 at the parabolic (odd) stage.

The paper presents the results of the study of the phase composition of hypereutectic silumin Al – 16.0 at. % Si – 0.2 at. % Fe. A comparative analysis of the phase composition of samples obtained at an average melt cooling rate of 102 K/s and at an ultra-high melt cooling rate of 105 K /s was carried out. At an average rate, the samples solidified in a graphite mold, and the ultra-high melt cooling rate was provided during the production of foils by the method of ultrafast quenching from the melt. It was established by X-ray diffraction and micro X-ray spectral analysis that the rapidly solidified foils consist of an aluminum-based solid solution supersaturated by silicon, dispersed silicon particles and the AlFeSi2 ternary compound phase. Comparative analysis of the results of X-ray diffraction and X-ray spectral studies of samples obtained at different melt cooling rates indicate that, during rapid solidification, the aluminum-based supersaturated solid solution contains up to 2 at. % Si.

The purpose of this study was to investigate (simulation of environment for salt treatment of roads in winter and the simulation of the environment of condensed exhaust gas) the galvanic corrosion phenomena which can exist in the construction coupling of cars. The electrochemical behaviour of the hot dip galvanized steel and aluminium alloy, stainless steel and aluminium alloy and stainless steel and silumin which were investigated by electrochemical methods in 3 % NaCl solution and in SEG solution. The open corrosion potential measurement was used to obtain the values of the potential for each couple. The measurement showed a greater bimetallic risk for hot dip galvanized steel with aluminium alloy, where there was ΔESCE > 500 mV and this couple is not suitable either for use in aggressive environment. Calculation of the rate of corrosion attack results from the determination of corrosion currents as measured by Taffel and Evans. The extent of corrosion damage was analysed by means of a light microscope. Keywords: bimetallic; aluminium alloy; stainless steel; silumin; exhaust gas; corrosion potential; electrochemical method

It is established that the electron-beam treatment of AK10M2N silumin by a pulsed electron beam with the specific energy of 35 J/cm2 leads to the increase in the surface layer microhardness from 0.99 up to 1.18 GPa with the simultaneous decrease in the friction coefficient by 1.3 times and in the wear coefficient by 6.6 times. After irradiation, a multilayer gradient structure is formed in the surface layer of the silumin. In the surface layer, there are no inclusions of the second phase, whereas in the deeper transient layer there are primary precipitations of intermetallic phase, which are the centers of aluminum crystallization. It is found that the changes in the mechanical and tribological properties of the silumin surface layers are associated with significant structural transformations, for instance, with the dissolution of silicon and intermetallics during irradiation of material with a high-intensity pulsed electron beam.