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This work deals with metastable and immiscible Cu-Fe alloys with different iron contents with a homogeneous microstructure were successfully prepared. Such a result was achieved using AISI 321 and C11000 steel and the multi-wire electron beam additive manufacturing. The samples under study were of different compositions with steel varying from 10 mass. % to 75 mass. %. The results showed that as the content of the second component increased, the volume fraction of stainless steel inclusions in the copper matrix increased, forming a heterogeneous melt. In the present work, a scheme of convective motion with diffusion elements in the melt pool at simultaneous feeding of two heterogeneous wires was constructed. During the melting process, the material with higher density occupies the lower position, displacing the less dense material to the upper part of the melt pool. Fluid phase separation processes due to surface tension also take place. After solidification, a heterogeneous melt is observed with the inclusion of copper in the steel matrix and steel in the copper matrix. After reheating, typical for electron beam additive manufacturing, secondary phases precipitate out of supersaturated solid solutions through the phenomenon of diffusion. [ABSTRACT FROM AUTHOR]

In the current work, samples of functionally graded materials based on steel and copper were obtained by wire-feed electron beam addition technique. The samples presented were characterized by a sharp and a smooth interface. To form the sharp interface, it was necessary to change the wire-feed from AISI 321 to C11000 immediately after finishing the N layer pass. Structure formation occurred through convective mixing and primary crystallization. Thus the formation of mechanical mixture on both sides of the sharp interface of functionally gradient material is observed. The width of the sharp interface does not exceed 100 µm. In order to form a smooth interface in the structure between the parts, it was necessary to gradually increase the feeding speed of the copper wire to the molten pool and decrease the feeding speed of the steel wire until it stopped completely. Structure formation in the material occurs through recrystallization and the formation of diffusion volumes, which leads to the presence of solid-phase diffusion. The width of the smooth interface between the components is from 6 mm, and this value can be increased by varying the wire feed rate ratios. [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]

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]

The bobbin-tool friction stir welding (BFSW) process is effective for welding aluminum alloys whose properties are determined by the structural-phase state. In this work, the evolution of the tool inlet area microstructure during the friction stir welding with a bobbin tool of a 20 -mm-thick plate made of AA2024 aluminum alloy was studied. Specific features of the welded joint formation at the initial stage in the central region of the weld and the near-surface one under the shoulder have been revealed. Regularities of the joint densification and structural changes in the material have been determined. [ABSTRACT FROM AUTHOR]