OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 1 2025 Results and Discussion Microstructure of the Experimental Cast Iron The microstructure of implanted metals and alloys is controlled by processes occurring in any supersaturated solid solution and by specific effects characteristic of the implanted metal surface. As a result of ion implantation, there is not just a simple surface coating, but a profound change in the structure of the material. Instead of a clear boundary between the new layer and the original material, as is typical with conventional deposition, a transition zone is formed. In this zone, the composition of the material gradually changes from the original cast iron to a modified layer enriched with nitrogen atoms. This changing composition creates a gradient of properties, where hardness and other mechanical characteristics smoothly transition from the initial values to the improved parameters achieved through ion implantation (Fig. 2). Nevertheless, from the photographs of the microstructure of the surface layer it is evident that a diffusion layer with a thickness of approximately 400 µm was formed on the surface of the implanted sample. Graphite inclusions are almost completely absent within this layer. These inclusions begin to appear only at the end of this layer and in small quantities. In the structure of grey cast iron graphite burnout occurs under the influence of nitrogen ions. Similar results were also obtained by the authors of the work [29]. In this work, nitriding of the surface of grey cast iron under different modes also led to the burnout of graphite inclusions in the surface layer of the samples. Implantation of nitrogen ions (N+) into the near-surface region of grey cast iron leads to significant changes in its microstructure. Firstly, fragmentation and disorientation of pearlite colonies occur, which are a characteristic feature of the microstructure of gray cast iron. The microstructure of the implanted cast iron is shown in Fig. 3. Fig. 2. Microstructure of the surface layer of cast iron implanted with N+ ions a b Fig. 3. Microstructure of the surface layer of cast iron implanted with N+ ions: a – 2×1017 ion/cm2; b – 1×1017 ion/cm2 The changes in the microstructure of the surface layer after ion implantation are crucial for determining various surface properties (microhardness, wear resistance, etc.). Microdurometry Analysis of Cast Iron after Implantation Microdurometry analysis showed that an increase in microhardness occurs as a result of ion implantation (Table 2, Figs. 4, 5, 6).
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