This work is dedicated to a comprehensive study of novel multi-component alloys (MCAs) Cu-Fe(Cr, Ni) and Cu(Al)-Fe(Cr, Ni), obtained using a wire and electron beam additive manufacturing (WEBAM), which were subjected to equal-channel angular pressing (ECAP). These materials are unique by their structure and phase composition as well as were for the first time subjected to ECAP. The results obtained in this study demonstrate that both alloys share the same microstructure composed of copper-base matrix and steel particles, their evolutions in ECAP diverge greatly. The presence of aluminum as alloying element of the bronze has its effect not only on microstructure and mechanical strength of the as-built bronze/stainless steel alloy but facilitates counter-diffusion of nickel and aluminum. The result is that Fe3Al κIV precipitates appear in the steel particles, while NiAl- κIII ones appear in the α-Cu(Al, Ni) matrix providing dispersion strengthening of both phases. This strengthening and twinning are the main reasons for strain localization in the form of shear bands and quasi-brittle behavior of ECAPed Cu(Al)-Fe(Cr, Ni) with an ultimate tensile strength of 321 MPa and plasticity of < 0.05. The ECAP also leads to an enhanced strength and hardness of the as-built materials, which is caused by strain hardening and grain refinement. Nevertheless, these samples demonstrated coefficient of friction and wear at the level of 0.1–0.2 mm and 0.2 mm (0.01 g) even after ECAP at 400 °C.

Regularities of structure formation of bimetallic elements of aluminum-manganese bronze CuAl9Mn2 and low-alloy structural steel A516 using different sequences of component deposition during printing by wire-arc additive manufacturing are investigated. It is found out that the sequence of material deposition affects the product structure and mechanical properties. Due to the differing melting points of bronze and steel, the samples show either a sharp fusion boundary between the components or their highly diluted mixture. According to the mechanical tests, the ultimate strength of the steel/bronze specimens reaches 450 MPa, while that of the bronze/steel specimens has lower values (220–350 MPa) due to the presence of defects.

The structure characteristics and the formation of properties of high-strength aluminum alloy 7075 are studied during friction stir welding of 3 mm thick plates. A possibility of forming a high-quality, permanent joint by the implementation of supplementary liquid cooling techniques during the welding process is shown. The tensile strength of the samples welded with water cooling is observed to exceed the base metal strength by 0.9 times. In the case of post-treatment aging, the strength of the welds is found to exceed that of the base metal.

The impact of heat input and scanning strategy during the printing of CuAl9Mn2 bronze by wire-arc additive technology on the structure, geometric parameters, and properties of the resulting products is examined. It is demonstrated that a higher rate of layer deposition results in enhanced mechanical properties of the material and smaller wall width and layer height. This enables the geometric parameters of the formed samples to be adjusted during printing. The deposition strategy also has a significant impact on the geometry of the products with round or rectangular cross-sections.

Composite materials based on a matrix copper alloy (CuAl9Mn2) have been obtained through the addition of low‐alloyed steel (13Mn6) in a volume fraction ranging from 5% to 95% by means of multiwire‐feed electron beam additive manufacturing. At the optimal manufacturing parameters, the samples exhibit no evidence of porosity, inclusions, imperfections, or delamination. It is shown that the addition of 13Mn6 steel, ranging from 5% to 95% by volume, influences the dendritic grain size, morphology, and mechanical properties. The primary factors influencing structure formation are the solidification of bronze inclusions in interdendritic regions or along the boundaries of steel dendrites, particularly when a smaller volume fraction of steel is added. In addition, the precipitation of small steel inclusions from the solid solution of copper in γ‐Fe is observed during cooling. In composites with a close ratio of bronze to steel, a homogeneous structure of bronze grains and steel dendrites is formed. The strength properties of the composites obtained are significantly superior to those of the matrix bronze. A moderate degree of anisotropy is observed between samples tested by static stretching in perpendicular directions.

The present paper compares the microstructure and mechanical properties of Inconel 625 alloy samples produced by using wire-arc additive manufacturing (WAAM) and wire electron beam additive manufacturing (WEBAM). The obtained wall-shaped samples did not contain any macroscopic defects in the form of cracks, delaminations and geometry distortions. The WAAM-built “wall” exhibits finer dendritic structures (WAAM—10–16 μm; WEBAM—20–25 μm). Also, the WAAM-built one is characterized by the more homogeneous-sized distribution of microstructure components. In both cases, the material is represented by the γ-phase, with large precipitates of MC-type carbides in the interdendritic spaces. Additionally, the sample obtained using the WAAM contained aluminum oxide. It was found that the intrinsic periodic heat treatment is not sufficient for the formation of the γ″-phase, and it is necessary to perform a subsequent long-term aging. However, the overall mechanical properties of both samples show similar levels of yield stress and ultimate tensile strength, and demonstrate the same degree of anisotropy.

This work is devoted to identify the specificity of plastic deformation, grain segmentation, plasticized fine-grained metal flow and texturing in a stirring zone formed between single crystalline and polycrystalline copper samples in friction stir welding (FSW). Inverse polar figures (IPFs) and orientation distribution functions (ODFs) were reconstructed from EBSD data obtained from different regions across the weld section. Thermomechanically affected zone (TMAZ) on the retreating side (RS) was formed by plastic deformation of single crystalline sample resulting in coarse–grained structures The stir zone (SZ) was mainly composed of small 1 to 3 μm grains and contained also coarse-grained up to 10 μm in size grain eddy-like structures. TMAZ on the advancing side (AS) had a typical fine-grained structure formed by flow of the SZ metal over the initial rolled copper structures. Preferential orientation of grains in these bands varied depending on their location in the stir zone. The fine-grained flow of metal and small differences in the grain orientation were found in bands close to both advancing and retreating sides of the stir zone. The central part of the stir zone showed the bands that resulted from both single- and polycrystalline copper samples, which had significantly different grain sizes and crystallographic orientations. The most complex pattern of the metal flow was found in the upper part of the stir zone, which underwent a combined deformation effect from the pin and the tool shoulder.

In this work, the characteristics of surface morphology and structure of experimental samples of nickel-based alloy and copper nozzles manufactured by the electron beam additive method have been studied. It is found that the grain boundaries on the outer sample surface are oriented at different angles relative to the substrate due to uneven heat dissipation during printing. It is found that 3D printing in a non-optimal temperature regime produces a highly heterogeneous structure within the material layer. A curvilinear boundary zone is observed in which different structural phase components are formed, including solid solutions and mechanical mixtures.

In the present work, a high-pressure spherical vessel was fabricated from Ti–4Al–3V titanium alloy using wire-feed electron beam additive manufacturing and characterized for tightness at high pressure. Studies have been carried out to characterize the microstructures and properties of the vessel’s material in four states: as-built (BM), annealed at 940 °C with cooling in air (HT1 treatment), quenched in water from 940 °C (HT2 treatment), and quenched with subsequent annealing at 540 °C (HT3 treatment). The microstructure of the as-built (BM) samples was composed of grain boundary α-Ti and α/β lath colonies located within the columnar primary β-Ti grain boundaries. The ultimate tensile strength of the as-built material was in the range of 582 to 632 MPa, i.e., significantly lower than that of the source Ti–4Al–3V alloy wire. The subtransus HT1 heat treatment allowed β→α″ transformation, while both HT2 and HT3 resulted in improved tensile strength due to the transformation of β-Ti into α/α′-Ti and the decomposition of α′ into α/β structures, respectively.

In this work, the interaction of an additively produced Ti-4Al-3V titanium alloy with a nickel superalloy tool and the features of the stir zone formation during friction stir processing have been studied. The stop-action technique was used to produce the samples to be studied using optical and scanning electron microscopy methods, as well as microhardness measurements. As a result, it was revealed that the tool, when moving, forms a pre-deformed area in front of it, which is characterized by a fine-grained structure. The presence of an interface layer between the workpiece material and primary fragmentation by the tool was revealed. It was demonstrated that the transfer of titanium alloy material occurs periodically following the ratio of feeding speed to tool rotation rate. Metal flow around the tool can occur in both laminar and vortex modes, as indicated by the tool material stirred into the transfer layer and used as a marker.

The introduction describes the features of the process of plasma cutting of various metals and alloys using reverse-polarity plasma torches with and the features of cutting thick sheets. The purpose of the work is to study the wear process of plasma torches operating on reverse polarity current when cutting thick rolled sheets of aluminum and titanium alloys. Research methods include optical and scanning electron microscopy, filming of the cutting process and visual inspection of plasma torch elements after receiving specimens. Results and discussion. The section shows the appearance of the main working elements of the plasma torch after cutting in various modes, which led to both stable and gradual wear and to catastrophic failure of the plasma torch. The results of structural studies of the main characteristic zones of nozzles and electrodes after cutting are presented. The studies carried out made it possible to establish the main reasons for the failure of the working elements reverse-polarity plasma torches. The causes of catastrophic failure of plasma torches include failure to maintain the gap between the nozzle and the electrode and melting of the channel of gas supply into the discharge chamber. The wear of nozzles and electrodes in a stable mode can be intensified due to abnormal operation of the starting arc, the presence of manufacturing inaccuracies and excess gas pressure. In conclusion, the main conclusions based on the results of the research are formulated. The process of wear of electrodes, nozzles and body elements of plasma torches during operation at high electric arc power values is described.

The structural features and phase composition were examined in near-surface layers in samples of Al-Mg, Al-Cu-Mg alloys and commercially pure titanium obtained by plasma cutting using direct current straight polarity (DCSP) and direct current reverse polarity (DCRP). It was found that the flows of molten metal carried away by the gas stream from the cut cavity during cutting form molten and heat affected zones, whose structural morphology, phase composition and thickness depend on both the selected material and the cutting mode. The thickness of the molten zone is larger for samples cut using DCRP than for those cut with DCSP. The thickness of the adjacent heat affected zone is also the greatest under conditions that provide a large thickness of the fused layer. Aluminum alloy samples cut in ambient air are characterized by the presence of oxygen in the near-surface layers. The lowest degree of oxidation is observed in Al-Mg alloy. Oxygen penetrates into the fused layer to a depth of 350-500 μm in Al-Cu-Mg and up to 200-250 μm in Al-Mg alloy. In titanium alloy, the thickness of the oxide layers does not exceed 100-150 μm when cutting with DCSP and 200-250 μm when cutting with DCRP. A thin brittle layer of TiO and TiO2 oxides is formed on the titanium alloy surface. It was shown that the release of “water mist” around the plasma jet when cutting materials of all types with DCRP leads to more intense oxidation of metal, less thermal effect on the material, and reduced roughness of the cut surface.

In order to gain insight into the unique characteristics of manufacturing large-scale products with intricate geometries, experimental nozzle-shaped samples were created using wire-feed electron beam additive technology. Bimetal samples were fabricated from nickel-based alloy and copper. Two distinct approaches were employed, utilizing varying substrate thicknesses and differing fabrication parameters. The two approaches were the subject of analysis and comparison through the examination of the surface morphology of the samples using optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. It has been demonstrated that the variation in heat flux distributions resulting from varying the substrate thicknesses gives rise to the development of disparate angles of grain boundary orientation relative to the substrate. Furthermore, it is demonstrated that suboptimal choice of the fabrication parameters results in large disparities in the crystallization times, both at the level of sample as a whole and within the same material volume. For example, for the sample manufacturing by Mode I, the macrostructure of the layers is distinguished by the presence of non-uniformity in their geometric dimensions and the presence of unmelted wire fragments. In order to characterize the experimental nozzle-shaped samples, microhardness was measured, uniaxial tensile tests were performed, and thermal diffusivity was determined. The microhardness profiles and the mechanical properties exhibit a higher degree of strength than those observed in pure copper samples and a lower degree of strength than those observed in Inconel 625 samples obtained through the same methodology. The thermal diffusivity values of the samples are sufficiently close to one another and align with the properties of the corresponding materials in their state after casting or rolling. The data discussed above indicate that Mode II yields the optimal mechanical properties of the sample due to the high cooling rate, which influences the structural and phase state of the resulting products. It was thus concluded that the experimental samples grown by Mode II on a thinner substrate exhibited the best formability.

The paper deals with friction stir welding of Grade 5 Ti alloy and AA2024 Al alloy sheets based on liquid cooling of welded joints. The metallographic analysis shows the mutual Al and Ti dissolution in the stir zone of the welded joint. The fractographic analysis of the surface shows a non-uniform fracture in the weld zone due to unwelded areas and a brittle fracture due to the presence of intermetallic components, which, in turn embrittle welded joints. By varying the parameters of friction stir welding, the adhesion between the materials is improved to obtain a joint with the highest possible strength.

This study presents interpretation and evaluation of a range of isothermal experimental crack growth data on polycrystalline XH73M nickel-based alloy generated by two type tests carried out by stress-controlled pure fatigue and creep-fatigue interaction conditions. The tests have been carried out using cycles with a triangular and trapezoidal waveform and a temperature range of 23-750°C. It was found that from the crack growth rate point of view, the following order of arrangement of fatigue fracture diagrams is formed: isothermal creep-fatigue interaction, isothermal pure fast (f=10 Hz) and slow (f=1 Hz) fatigue. The ordering of the crack growth rate curves is supported by detailed fractographic analysis which shows transgranular or intergranular mechanism of fatigue crack growth depending on thermo-mechanical test conditions. The regularities of fatigue crack propagation were established by fractographic analysis. It was found for example that the intergranular crack growth mechanism become dominant at 750°C for the pure fatigue and at 550°C for creep-fatigue interaction conditions. The secondary crystals on the grain boundary of primary grain at intergranular fracture of specimen tested at 650°C under creep-fatigue interaction conditions appeared.

The work is devoted to a review of modern achievements in the field of wire-feed electron beam additive manufacturing. The features of structure formation in aluminum, copper, titanium, nickel-based alloys, and steels during 3D printing are shown. Aspects of directional solidification during the production of components from various metals and alloys are considered. The prospects for obtaining composite and functionally graded materials based on various metals and alloys using wire-feed electron beam additive manufacturing are determined. The regularities of the structure modification and hardening of additively manufactured materials by the method of friction stir processing were considered. The main purpose of the review is to present additive manufacturing methods, the main focus being on the wire-feed electron beam additive manufacturing of metal alloys.

The peculiarities of defect formation in composite materials based on Grade 2 titanium alloy formed by friction stir processing with an addition of pure copper powder particles are studied. The results show that a macroscopically inhomogeneous structure is formed in the samples, which depends both on the number of tool passes along the processing line and on the volume fraction of the powder material added into the stir zone. The main stir zone defects include beading (flash), penetration of substrate fragments, formation of discontinuities and cracks. The stir zone homogeneity can be improved by increasing the number of tool passes along the processing line. However, in the case where the volume fraction of the added powder is large, even a multi-pass mode might fail to achieve a homogeneous stir zone structure.

The compensation of rotation makes it possible to diminish the deformation measurement error, and appropriate choice of the constant vector diminishes the sum of the vector components. This allows also to characterize a vector field by its mean length (algebraic or modulus) and related standard deviation. This approach was tested by the digital image correlation (DIC) technique by the example of porous ceramics in compression. The first fracture stage (0.006 ≤ ε ≤ 0.015) is related to local strain accumulation in the upper and lower parts of a specimen. The second stage (0.015 < ε ≤ 0.047) is the stage of stable ceramics flow. At the third stage (0.047 < ε ≤ 0.063), the unstable inelastic deformation is developed and accompanied by fragmentation or local vortices. The fourth stage (0.063 < ε ≤ 0.078) is characterized by nonlinear phenomena. Each stage has its typical deformation-induced structure, mean vector length rate, and standard deviation. Fracture mechanisms of the ceramics are investigated, and deformation structures are given. These amplitude characteristics vary by two or three orders of magnitude. As shown, the normalized standard deviation changes slightly, so it could be considered as a constant for the ceramics.

This paper is devoted to using multi-pass friction stir processing (FSP) for admixing 1.5 to 30 vol.% copper powders into an AA5056 matrix for the in situ fabrication of a composite alloy reinforced by Al-Cu intermetallic compounds (IMC). Macrostructurally inhomogeneous stir zones have been obtained after the first FSP passes, the homogeneity of which was improved with the following FSP passes. As a result of stirring the plasticized AA5056, the initial copper particle agglomerates were compacted into large copper particles, which were then simultaneously saturated by aluminum. Microstructural investigations showed that various phases such as α-Al(Cu), α-Cu(Al) solid solutions, Cu3Al and CuAl IMCs, as well as both S and S’-Al2CuMg precipitates have been detected in the AA5056/Cu stir zone, depending upon the concentration of copper and the number of FSP passes. The number of IMCs increased with the number of FSP passes, enhancing microhardness by 50–55%. The effect of multipass FSP on tensile strength, yield stress and strain-to-fracture was analyzed.