This paper discusses a comparative micromechanical and tribological analysis of laser-cladded equiatomic FeNiCr coatings reinforced with TiC and NbC particles. Two types of coatings, FeNiCr-TiC (3 wt.% TiC) and FeNiCr-NbC (3 wt.% NbC), were deposited onto an AISI 1040 steel substrate by means of short-pulsed laser cladding. The chemical composition, microstructure, and micromechanical and tribological characteristics of the coatings were systematically investigated via optical and scanning electron microscopy, Raman spectroscopy, and mechanical and tribological tests. The average thicknesses and compositional transition zones of the coatings were 600 ± 20 μm and 150 ± 20 μm, respectively. Raman spectroscopy revealed that both coatings are primarily composed of a single FCC γ-phase (γ-FeNiCr). The FeNiCr + 3 wt.% TiC coating exhibited an additional TiC phase dispersed within the γ-FeNiCr matrix. In contrast, the FeNiCr + 3 wt.% NbC coating displayed a more homogeneous distribution of finely dispersed NbC phase throughout the composite, leading to enhanced mechanical behavior. Micromechanical characterization showed that the FeNiCr + 3 wt.% NbC coating possessed higher average microhardness (3.8 GPa) and elastic modulus (180 GPa) compared to the FeNiCr + 3 wt.% TiC coating, which had values of ~3.2 GPa and ~156 GPa, respectively. Both coatings significantly exceeded the AISI 1040 steel substrate in tribological performance. The FeNiCr + 3 wt.% TiC and FeNiCr + 3 wt.% NbC coatings exhibited substantial reductions in both weight loss (37% and 41%, respectively) and wear rate (33% and 42%, respectively) compared to the substrate material. These findings indicate that more finely dispersed NbC particles are better suited for hardening laser-cladded equiatomic FeNiCr-NbC coatings, making them advanced candidates for industrial applications.

This study elucidates the dynamic tribo-mechanical response of laser-cladded FeNiCr-B₄C metal matrix composite (MMC) coatings on AISI 1040 steel substrate, unraveling the intricate interplay between microstructural features and phase transformations. A multi-faceted approach, employing high-resolution scanning electron microscopy (SEM) and advanced X-ray diffraction/Raman spectroscopy techniques, provided a comprehensive characterization of the coatings’ behavior under mechanical and scratch testing, shedding light on the mechanisms governing their wear resistance. Specifically, microstructural analysis revealed uniform coatings with a columnar structure and controlled defect density, showcasing an average thickness of 250 ± 20 μm and a transition zone of 80 ± 10 μm. X-ray diffraction and Raman spectroscopy confirmed the presence of α-Fe (Im-3m), γ-FeNiCr (Fm-3m), Fe₂B (I-42m), and B₄C (R-3m) phases, highlighting the successful incorporation of B₄C reinforcement. The addition of 5 and 7 wt.% B₄C significantly increased microhardness, showing enhancements up to 201% compared to the B₄C-free FeNiCr coating and up to 351% relative to the AISI 1040 steel substrate, respectively. Boron carbide addition promoted a synergistic strengthening effect between the in situ formed Fe₂B and the retained B₄C phases. Furthermore, scratch test analysis clarified improved wear resistance, excellent adhesion, and a tailored hardness gradient. These findings demonstrated that optimized short-pulsed laser cladding, combined with moderate B₄C reinforcement, is a promising route for creating robust, high-strength FeNiCr-B₄C MMC coatings suitable for demanding engineering applications.

Problem. Alloys of the NiCrBSi system are widely used for gas-thermal spraying of protective coatings due to their low melting point. However, coatings formed by high-velocity gas-thermal spraying are characterised by residual porosity and a layered structure, which limits their strength properties. A literature review revealed a lack of systematic data on the influence of subsequent high-temperature annealing on the transformation of the structural-phase composition, continuity, and the complex of micromechanical characteristics of such coatings. Aim. To evaluate the effect of vacuum annealing at 1050 °C on the structural-phase composition, continuity, and micromechanical properties (microhardness, Martens hardness, contact elastic modulus) of NiCrBSi coatings produced by high-velocity gas-thermal spraying. Methods. NiCrBSi alloy coatings were deposited by high-velocity gas-thermal spraying. The samples were subjected to vacuum annealing at 1050 °C with an isothermal hold of 2 h and subsequent furnace cooling. The study of structural-phase changes was carried out using scanning electron microscopy, X-ray phase analysis, and energy-dispersive X-ray microanalysis. Micromechanical properties were evaluated by measuring microhardness (recovered indentation method) and instrumented microindentation. Results. It was experimentally confirmed that annealing at 1050 °C leads to the formation of a dense homogeneous structure without layering. The formation of large strengthening phases – carbides (Cr7C3 and Cr23C6) and CrB chromium borides – was recorded, which increases the strength characteristics of the coating during indentation by 25–30 %. It was found that the contact elastic modulus increases from 130 to 228 GPa due to the elimination of discontinuities. Additional heating to 900 °C does not cause changes in the structure and hardness, which confirms the high thermal stability of the coating subjected to high-temperature (at 1050 °C) annealing. Conclusions. Hightemperature vacuum annealing at 1050 °C is an effective post-treatment method for sprayed NiCrBSi coatings, providing a 1.3-fold increase in hardness and a 1.7-fold increase in the elastic modulus due to the formation of larger strengthening phases and a reduction in the number of discontinuities.

The influence of tungsten carbide and boride additives on the structure and microhardness of CrFeNi equiatomic coating formed by short-pulse laser cladding Влияние добавок карбида и борида вольфрама на структуру и микротвердость эквиатомного CrFeNi-покрытия, сформированного короткоимпульсной лазерной наплавкой