PSI - Issue 81

Pavlo Prysyazhnyuk et al. / Procedia Structural Integrity 81 (2026) 216–220

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Fig. 1. X-ray diffraction pattern of the Fe-NbC system coating.

Thus, the observed interconnected changes in the crystal lattice parameters of both phases provide compelling evidence of active diffusion processes and limited mutual dissolution of the components at the "carbide-matrix" interface during the formation of the composite layer. The structure of the Fe-NbC system coating (Fig. 2 , a) consists of dispersed (~5 μm in size) faceted carbide phases, which are distributed quite uniformly in the steel matrix. In this case, the steel matrix does not contain regions with distinct pearlite colonies and cementite, which are typical for carbon steels. The microstructure corresponds to the results of thermodynamic calculations (Fig. 2, b). The average microhardness near the fusion zone, measured from the side of the deposited layer, is relatively high at ~3.8 GPa. The bulk macrohardness of the coating was determined to be 40 HRC. At the same time, the fusion zone (Fig. 2, c) is characterized by continuity, the absence of visible defects (under microscopic examination), and a smooth transition from the substrate to the coating. According to the calculated redistribution of elements between the phases, the solubility of Fe in the carbide phase is low (< 1 at. %), which should not negatively affect its wear resistance level (Fig. 2, d).

Fig. 2. Analysis of the structural evolution and phase characteristics within the Fe-NbC system coating: (a) Microstructure of the as-deposited coating, (b) Calculated equilibrium phase composition, (c) Morphology of the coating-substrate fusion zone, and (d) Equilibrium elemental composition of identified phases.