OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 3 2025 modes 1 and 3, and 5 mm for mode 2. For microstructural analysis, the bimetallic specimen was sectioned along a plane perpendicular to the direction of layer growth. The homogeneous layers produced from chromium-nickel steel or nickel-based alloy powder exhibit a characteristic dendritic microstructure with the formation of both equiaxed and columnar dendrites. At the interfaces between successive layers and near the boundaries of the deposited structure, where heat dissipation was more intense, columnar dendrites predominate. These dendrites are typically characterized by the presence of secondary arms (Fig. 3). At the edges of the deposited structures, regardless of the processing mode, spherical particles with diameters ranging from 25 to 40 μm were observed (Figs. 4, a, b). These are unmelted or partiallymelted particles of the original powder, which is a characteristic feature of the direct laser deposition (DLD) process [17, 18]. In addition, the formation of cracks was noted both at the interface between dissimilar materials (Fig. 4, c, d) and at the fusion boundaries between similar materials. This phenomenon is attributed to thermal stresses that arise during the formation of dissimilar gradient materials. Fig. 2. Example of a fabricated specimen a b с d Fig. 3. Location of elongated dendrites: a – transition layers boundary; b – dissimilar material interface; c – layer edge; d – secondary arms in elongated dendrites
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