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The paper presents a study of morphology and chemical composition of the TiNbZrSi powder customized by mechanoactivation in an experimental high-energy vibration ball mill equipped with steel mortars and balls of different diameters. The initially synthesized as-cast TiNbZrSi tablet was preliminarily ground into a powder with fraction of about 400 µm using a conventional bench hammer. After that, the above powder was subjected to mechanoactivation within 4 hours in an Ar atmosphere at room temperature. In addition, the synthesized TiNbZrSi powder was deposited onto additively manufactured Ti-6Al-4V ELI substrates through their co-mechanoactivation followed by annealing for 1 hour at a temperature of 800 °C to ensure better adhesion. The characterization of the TiNbZrSi powder before and after co-mechanoactivation with the specified substrate was carried out by scanning electron microscopy.

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. [ABSTRACT FROM AUTHOR]

Equiatomic medium-entropy alloy (MEA) FeNiCr-B4C (0, 1, and 3 wt.% B4C) coatings were deposited onto an AISI 1040 steel substrate using pulsed laser cladding. Based on an SEM microstructural analysis, it was found that the cross-sections of all the obtained specimens were characterized by an average coating thickness of 400 ± 20 μm, a sufficiently narrow (100 ± 20 μm) "coating–substrate" transition zone, and the presence of a small number of defects, including cracks and pores. An XRD analysis showed that the formed coatings consisted of a single face-centered cubic (FCC) γ-phase and the space group Fm-3m, regardless of the B4C content. However, additional TEM analysis of the FeNiCr coating with 3 wt.% B4C revealed a two-phase FCC structure consisting of grains (FCC-1 phase, Fm-3m) up to 1 µm in size and banded interlayers (FCC-2 phase, Fm-3m) between the grains. The grains were clean with a low density of dislocations. Raman spectroscopy confirmed the presence of B4C carbides inside the FeNiCr (1 and 3 wt.% B4C) coatings, as evidenced by detected peaks corresponding to amorphous carbon and peaks indicating the stretching of C-B-C chains. The mechanical characterization of the FeNiCr-B4C coatings specified that additions of 1 and 3 wt.% B4C resulted in a notable increase in microhardness of 16% and 38%, respectively, with a slight decrease in ductility of 4% and 10%, respectively, compared to the B4C-free FeNiCr coating. Thus, the B4C addition can be considered a promising method for strengthening laser-cladded MEA FeNiCr-B4C coatings. [ABSTRACT FROM AUTHOR]