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In the present work the influence of technological parameters of wire-feed electron beam additive manufacturing on the size of γ'-phase precipitations the in the product of Ni-Al system of a heat-resistant nickel-based superalloy was investigated. It was shown that the size of γ'-phase precipitations in the form of nanoscale and submicrocrystalline cuboids in the material of the additively formed product was smaller than in the initial as-cast state. Depending on the distance to the substrate, the average size of cuboids ranged from 43 to 207 nm, which was 13 to 2.7 times smaller than in the as-cast state. It was found that, depending on the height of the additive product, the size of γ'-phase precipitations reached an extremum at a distance of about 20 mm to the substrate. The average size of γ'-phase cuboids did not exceed 133 nm in the final material layers of the additive product with a height of 34 mm. The extreme dependence of the size of γ'-phase precipitations along the height of the additive product was caused by a combination of a given monotonic decrease in the heat input and heat accumulation in the product material as it was being formed. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the transition layer structure of bimetallic samples based on the nickel heat-resistant alloy Udimet500 and the heat-resistant bronze CuCr1. When printing the bronze part on top of the nickel part, the nickel is melted and kneaded into the bronze part at a distance of up to 5 mm. When printing the nickel part on top of the copper part, the size of the transition zone does not exceed 2-2.5 mm. No cracks or discontinuities were detected at the boundary of the nickel and bronze areas. In the transition zone due to the formation of fine grain structure reinforced by nickel alloy particles the mechanical properties of the bronze increase, resulting in the destruction of samples outside the boundary part inside the bronze. [ABSTRACT FROM AUTHOR]

Avoiding the formation of epitaxially grown coarse columnar primary β-Ti grains during additive manufacturing is a critical issue. Columnar β-Ti grains are generally considered unfavorable because their presence can lead to anisotropy and deterioration of mechanical properties, but the thermal conditions encountered in additive manufacturing make its prevention difficult. In this work, the effect of different Cu concentrations on the grain structure formation and mechanical properties of Ti6Al4V fabricated via electron-beam additive manufacturing with simultaneous double-wire feeding was investigated. It was found that the addition of 2.6 vol.% Cu to Ti6Al4V leads to a significant reduction in the size of the primary columnar β-Ti grains. With the addition of 7.5 vol.% Cu in Ti6Al4V the transition from large columnar grains to equiaxed grains is observed, as well as an increase in microhardness and ultimate tensile strength by 13 % and 24 %, respectively. Such effect is achieved by fine-grain hardening, solid solution hardening and dispersion hardening. At the same time, relative elongation decreased by 3.3 times in comparison with additive Ti6Al4V without copper. [ABSTRACT FROM AUTHOR]

This work investigates the peculiarities of structure formation in the stir zone during friction stir processing on workpieces produced by electron-beam additive manufacturing of Ti-6Al-4V alloy. For this purpose, 30-mm-high workpieces were 3D-printed and then processed by FSP in different directions relative to the wall growth direction. The studies showed that the primary structure of the material affects changes in the tool effect area. In the wall growth direction (GD), in the area in front of the tool, material deformation was observed at a distance of 0.2 mm from the tool outlet, while in the layer deposition direction (DD) - at 0.45 mm. It was shown that in the GD, the specimen cut in the center of the stir zone has the adhesion zone equal to 120 µm, 125 µm, and 205 µm on the advancing side, in the area in front of the tool, and on the retreating side, respectively. At the same time, in the DD, the adhesion zone equals 90 µm, 100 µm, and 390 µm, respectively. The bands revealed by etching in the stir zone result from the adhesion-diffusion transfer of the titanium alloy by the tool made of nickel-based heat-resistant alloy ZhS6U. [ABSTRACT FROM AUTHOR]

In the work samples of composite materials were obtained by two-wire printing by electron beam additive manufacturing. In the process of obtaining the samples the peculiarities of the composite structure and typical areas of localization of the intermetallic phases and solid solutions formation were determined. It has been revealed that the formation of continuous large intermetallic interlayers produces defects in the form of micro-and macroscopic sized cracks. According to X-ray diffraction analysis, the main intermetallics in the samples are Cu9Al4, Cu4Al and Cu3Al. Forming intermetallic phases of various types can be localized at the grain boundaries, form honeycomb structures and continuous layers. [ABSTRACT FROM AUTHOR]

The paper shows the peculiarities of changes in the structure and properties in the composite material based on aluminum alloy 5056 during friction stir processing with the introduction of 1.5 vol.% pure copper powder. It has been revealed that with small additions of copper powder even starting from a small number of passes by the tool along the machining line a fairly uniform distribution of particles in the volume of the stir zone is achieved. The mechanical properties during machining with the 1st pass are reduced relative to the properties of the base metal. After the 3rd pass, the material properties are already at the level of the base metal properties. After the 4th pass, an increase in strength relative to the base metal is achieved. It is noteworthy that even after 4 passes along the machining line, small amounts of pure copper unreacted with the base metal remain in the structure of the stir zone. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental work on the development of the technique for obtaining composite material on the basis of aluminum-manganese bronze CuAl9Mn2 with the introduction of 5-25% of the nickel alloy Udimet500 during printing. The results obtained testify to a high degree of applicability of the two-wire electron-beam printing technology to composites of the bronze-nickel system with different contents of strengthening phases. There were no defects in the form of cracks or delaminations in the samples. The defect-free structure was obtained by empirical selection of printing process parameters and geometry of wire input into the melt bath. Increasing the volume fraction of the input nickel alloy resulted in an increase of the tensile strength up to 700 MPa. Intermetallic NiAl and Ni3Al as well as M23C6 carbides formed in the structure in large amounts. Also particles with a complex structure of intermetallides and carbides were found. [ABSTRACT FROM AUTHOR]

This work obtained a hardened surface layer on the surface of 4Cr9Si2 steel in the process of additive electron beam 3D-printing with the combination of wire and powder feeding of the material into the printing zone. It is revealed that tungsten particles after printing are located mainly in the interdendritic space of the steel. A number of macroscopic inhomogeneities are present in the layer volume. A small-sized transition zone with a mixed structure is formed along the contour of fine powder particles. The orientation of growing dendrites both in the base metal and in the hardened layer has a pronounced direction in the direction of heat removal from the melt bath of each layer. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the structure organization in composite materials based on copper and copper alloys when produced by electron beam additive technology with the adding of hardening phases using two-wire feeding and with the combined feeding of wire and powder. The conducted studies show the differences in the structure organization and typical defects depending on the way of hardening phases introduction. It is shown that both methods of composite material formation have a number of advantages and disadvantages. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the influence of the degree of mutual solubility of metals and alloys in obtaining composite materials with a metal matrix on the organization of the structure. The studies show that for materials with different degrees of mutual solubility of components the organization of the structure differs significantly, which must be taken into account when making products with composite structure. Samples based on components with limited mutual solubility are most susceptible to cracking, especially with excessive formation of intermetallic phases. When obtaining composite materials based on alloys, formation of secondary phases is possible not between the main components, but between the alloying elements. The melting temperature and density of the components, which additionally determine the structure organization of the samples, also have a significant influence when obtaining composites. [ABSTRACT FROM AUTHOR]